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SPD-RAG: Sub-Agent Per Document Retrieval-Augmented Generation

YagizCanAkay1 MuhammedYusufKartal1 EsraAlparslan1
FarukOrtakoyluoglu1 ArdaAkpinar2
1TOBBUniversityofEconomicsandTechnology 2OSTIMTechnicalUniversity
{y.akay, m.kartal, ealparslan, fortakoyluoglu}@etu.edu.tr 230206003@ostimteknik.edu.tr
Abstract andcommon,yetexposecriticalcoverageandrea-
--- --- -------- --- --- ------------------------------------------ --- --- --- --- --- ---
soningbottlenecksincurrentNLPsystems.
Answeringcomplex,real-worldqueriesoften
6202 raM 9 ]LC.sc[ 1v92380.3062:viXra Traditionalsingle-indexorsingle-agentretrieval
requiressynthesizingfactsscatteredacrossvast
systemsstruggleto maintainbothscalability and
-------- -------- -------- --------- ----- ----------------- --- ----------------------- --- --- --- ---
document corpora. In these settings, stan-
contextualrelevanceoverlarge,heterogeneouscor-
dard retrieval-augmented generation (RAG)
------------------------ --- --- ---------- ----- ---------------- --- -------- --------------- --- ------- ---
pora, especially for long or structurally complex
pipelinessufferfromincompleteevidencecov-
erage,whilelong-contextlargelanguagemod- documents. Standard RAG pipelines retrieve a
fixed number of documents K and process them
---------- -------- --------- -------- ---- ------------ --- ------------ --- ----------- --- ----
els (LLMs) struggle to reason reliably over
massive inputs. We introduce SPD-RAG, a withinasinglecontextwindow(Lewisetal.,2020),
hierarchicalmulti-agentframeworkforexhaus-
whichfailswhenanswersdependoninformation
tivecross-documentquestionansweringthatde-
distributedacrossmanydocuments,sinceevidence
composestheproblemalongthedocumentaxis.
beyondthetop-K resultsistypicallydiscardedin
---- -------- ------------ ---- --------- -------------- --------- ----------------------------- ------------ --- ---- ---
Each document is processed by a dedicated
a single retrieval pass. Long-context LLMs ex-
document-levelagentoperatingonlyonitsown
content,enablingfocusedretrieval,whileaco- tendcontextwindowsto128K–2Mtokens(Gemini
Teametal.,2024), butempiricalevidenceshows
--------- ---------- ----- ----------- ------ ---------------- --- ------------------------- --- --- --- ---
ordinator dispatches tasks to relevant agents
and aggregates their partial answers. Agent thatreasoningqualitydegradessignificantlyascon-
outputsaresynthesizedbymergingpartialan- text length increases (Liu et al., 2023). This sug-
swersthroughatoken-boundedsynthesislayer
gests that the bottleneck is not only retrieval, but
--- --- --- --- --- ---------- --- ---------- ------ ---- ---------- ---
(whichsupportsrecursivemap-reduceformas-
alsoreasoningatscaleovermanydocumentsand
sivecorpora). Thisdocument-levelspecializa-
------------- --- ----------------------------- --- --- --- --- --- --- --- --- ---
hundredsofthousandsoftokens.
tionwithcentralizedfusionimprovesscalabil-
ityandanswerqualityinheterogeneousmulti- In this work, we introduce SPD-RAG
(Sub-agent per Document Retrieval-Augmented
-------- -------- ----- -------- ---------- ---------- --- -------- ------------------- --- --- ---
document settings while yielding a modular,
extensibleretrievalpipeline. OntheLOONG Generation),ahierarchicalmulti-agentarchitecture
benchmark (EMNLP 2024) for long-context forexhaustivemulti-documentquestionanswering
multi-document QA, SPD-RAG achieves an thatfactorstheproblemalongthedocumentaxis
AvgScoreof58.1(GPT-5evaluation),outper-
rather than the task axis. Instead of forcing a
--- --- --- --- --- ----------- --- ---------- ------- --- ---------- ---
formingNormalRAG(33.0)andAgenticRAG
single model to hunt through a massive global
--- --- --- --- --- ------------ --- --------------- --- --------- --- ------
(32.8)whileusingonly38%oftheAPIcostof
index, SPD-RAG uses a central coordinator to
--- --- --- --- --- -------------- --- ---- --------- ----------- --- ---
afull-contextbaseline(68.0).
decompose the user’s query into shared instruc-
--- --- --- --- --- --------- --- ------ ---------- ------ -------- ---
1 Introduction tions. It then deploys a dedicated, cost-efficient
sub-agenttoeachdocumentinthecorpus. These
--- --- --- --- --- ----------------------------------- --- --- --- --- --- -----
Large language models (LLMs) and the agentic agents operate entirely in parallel, treating their
systems built around them are increasingly used assigneddocumentsasisolatedretrievaluniverses
forcomplexinformationsearchtasks(Guoetal.,
to extract relevant findings. Finally, a synthesis
--- --- --- --- --- ---------- -------- --------- -------- --- ----------- ---
2024). Real-worldquestionsoftenrequiresynthe-
model aggregates these document-grounded
--- --- --- --- --- ----- ---------- ----- ----------------- --- --- ---
sizingevidencescatteredacrossmanydocuments, findings—employingarecursivemergingfallback
suchasassessingacompany’sfinancialrisksacross
for exceptionally large corpora—to construct a
--- --- --- --- --- ----------------- --- ----- ---------- --- --------- ---
yearsofreportsorintegratingfindingsfrommul-
comprehensive, final answer. Our codebase and
--- --- --- --- --- -------------- --- ------------- --- ------------ --- ---
tiplescientificpapers.1
Suchquestionsarenatural datasetsusedinthispapercanbefoundat
--- --- ----------------------- --- --- ----------------------------------- --- --- --- --- --- ---
https://github.com/NebulAICompany/
1Examples inspired by scenarios in the Loong bench-
---------------------- -------- ------------ ------ ------------ -------- --- --- --- --- --- ---
mark(Wangetal.,2024a). SPD-RAG.

Ourcontributionsareasfollows: tasks,butthatmulti-agentoverheadgrowssuperlin- early. Theirresultthatindependentagentsamplify • WeproposeSPD-RAG,ahierarchicalmulti- errorsby17.2×comparedto4.4×forcentralized agentframeworkthatcombinesper-document systemsdirectlymotivatesourcoordinator-based agentic RAG with a centralized synthesis design. Thetaxonomyofhierarchicalmulti-agent layer, where cost-efficient document agents systemsbyMoore(2025)furtherclassifiesdesign

are coordinated by a smarter coordinator
patternsalongfiveaxes: controlhierarchy,informa-
agent,enablingdocument-levelspecialization
tion flow, role delegation, temporal layering, and
----------------- -------------- --------------- --------- ----------------------- ---------------- -------- --------- ---
and parallel execution while allowing each communicationstructure.
document to be analyzed in depth to ensure
that all relevant information is incorporated
2.2 LongDocumentandMulti-DocumentQA
withoutmissingcriticalevidence.
Long documents that exceed LLM context win-
--- --- --- --- -------------- ---- ------ ----------- ----
• WeevaluateontheLoongbenchmark(Wang
dows are often handled via divide-and-conquer
--- --- --- --- -------- ------------- --- ------------------ ---
etal.,2024a),whichincludesmulti-document
strategies. LLM×MapReduce(Zhouetal.,2025)
------------ -------------- ---------- -------- --------------------------- ----------------------------- --- ----------------- ---
QA instances over financial reports and aca-
formalizestwokeychallenges: inter-chunkdepen-
demic papers with an average of 11 docu-
dency(onechunkdependsoncontextfromanother)
mentsperinstanceandcontextlengthsfrom
andinter-chunkconflict(chunksprovidecontradic-
10K to beyond 250K tokens, and show that
------------- ---- ----------- --------- --- --- --- --- ---
toryinformation),andproposesstructuredinforma-
oursystemsubstantiallyoutperformsstandard
tionprotocolsandin-contextconfidencecalibration
RAGandAgenticRAGbaselinesunderGPT-
tomitigatethem. ToM(Guoetal.,2025)extends
-------- ------------------ ---- ------- --------------- ------------------------- ------------ ------- ------
5-judged Avg Score (adapted from Loong’s
this approach with a hierarchical DocTree repre-
GPT-4-judgedprotocol;see§4.3),withgains
sentationforrecursivereasoning.
of around +25 points (76% higher average
--------- ---------- ----------- ------- --- --- --- --- ---
Formulti-documentQA,LongAgent(Zhaoetal.,
score)comparedtoNormalRAGandAgentic
2024) splits a 128K-token document into chunks
--- --- --- --- ------------ ------------ -------- --- -----------
RAGbaselines.
assigned to member agents, with a leader agent
--- --- --- --- ------------- -------------- ------------ ---------------- -----
orchestrating discussionsand inter-membercom-
• Weanalyzeablations,documenttypeandtask
complexityeffects,andcost–qualitytradeoffs, munication to reduce hallucinations. However,
showingthat SPD-RAGattainsover85%of LongAgenttargetsasinglelongdocumentrather
thanmultipleindependentdocumentsthatmaycon-
full-context baseline quality at roughly 38%
------------ ---------------- ---------- --- --------------- ---- ------------- ---- --------
flict. DocAgent (Sun et al., 2025) uses a multi-
oftheAPIcost.
agent framework that mimics human reading via
--- --- --- --- --------------- ---- ------ ----- -----------
2 RelatedWork
atree-structuredoutlineandrevieweragent,while
MDocAgent (Han et al., 2025) employs five spe-
--- --- --- --- --------- ------- ---------- ------- ---------
2.1 LLM-BasedMulti-AgentSystems
cialized agents for multi-modal document under-
--- --- --- --- -------- ---------------------- --- -------- ------
LLM-basedmulti-agentsystemsareincreasingly
standing.
used for complex task solving. Guo et al. (2024)
---------------- ------------- ------ ---------- --- --- --- --- ---
provideacomprehensivesurveyofagentprofiles,
2.3 HierarchicalandRecursive
communicationprotocols,andcollaborationstrate-
Summarization
gies. Hierarchical architectures such as MegaA-
------------------ ------------- ---- --------- --- --- --- --- ---
gent(Wangetal.,2024b),whichdemonstratesau- Ourhierarchicalmergingmechanismbuildsontree-
tonomouscooperationamongupto590agentsvia basedretrievalandrecursivesummarization. RAP-
multi-leveltaskdecomposition,andAgentOrches- TOR(Sarthietal.,2024)recursivelyembeds,clus-
tra(Zhangetal.,2025),whichachievesstate-of-the- ters, and summarizes text chunks to construct a
artperformanceonGAIAusingacentralplanning bottom-uptreewithmultipleabstractionlevels;re-
agent and specialized sub-agents, exemplify this trievingfromtheappropriatelevelyieldsa20%ab-
trend. soluteaccuracygainonQuALITY.OuandLapata
------ --- --- --- --------------------------------------- --- --- --- ---
Scalinglawsformulti-agentsystemsofferquan- (2025)showthathierarchicalmergingcanamplify
titativeguidanceforarchitecturedesign. Kimetal. hallucinationsduringrecursivesummarizationand
(2025)evaluate180configurationsacrossfivear- proposecontext-awareaugmentationstrategiesthat
chitectures, finding that centralized coordination replaceintermediatesummarieswithrelevantinput
yields an 80.9% improvement on parallelizable context,whichweadoptinourmergingprotocol.

2.4 Graph-BasedDocumentAnalysis 3 Methodology Figure 1 presents an overview of the SPD-RAG Graph-based document analysis is particu- architecture. Thesystemprocessesaquerythrough larly effective for global sensemaking queries. three layers: the Coordination Layer (§3.1), the GraphRAG(Edgeetal.,2024)constructsaknowl- ParallelRetrievalLayer(§3.2),andtheSynthesis edge graph of entities and relations from source Layer(§3.3). documents and applies hierarchical community detection(e.g.,theLeidenalgorithm(Traagetal., 3.1 CoordinationLayer 2019)) to obtain multi-level communities with Given a query q and corpus D, the system first textual summaries. At query time, it retrieves processes the query through a coordinator agent. relevant communities, elicits community-level The coordinator’s role is to decompose the user partial answers, and aggregates them via a query into a Shared Instruction Set for Docu- map–reduce–styleprocedure. AsurveyonLLM- ments and Synthesis Directives. It generates a empoweredknowledgegraphconstruction(Bian, WriteTodosstructuredobjectcontaining(a)alist 2025) highlights how LLMs are reshaping the of sub_agent_todos: atomic, self-contained ex- classical knowledge graph pipeline across three traction tasks specifying exactly what fields, en- key stages: ontology engineering, knowledge tities, or numeric values to extract (the shared in- extraction, and knowledge fusion. Our work is structions);and(b)asynthesis_directive(2–4 complementary: instead of inducing an explicit sentences) instructing the downstream Synthesis knowledge graph, SPD-RAG operates directly Layeronhowtoprioritizeandstructurethemerged over agent-produced textual summaries and response. performs similarity-guided recursive synthesis acrossmanydocuments. 3.2 ParallelRetrievalLayer Weassignadedicatedsub-agentα toeachdocu- i mentd inthecorpus. Eachsub-agentoperatesas 2.5 BenchmarksforMulti-Document i anindependentRAGloopoveritsassigneddocu- Reasoning ment,guidedbythesharedinstructionsetfromthe The Loong benchmark (Wang et al., 2024a) CoordinationLayer. evaluates long-context LLMs on extended multi- Document-Scoped Retrieval and Reasoning. document QA where every document is relevant Each document d serves as an isolated retrieval i ("Leave No Document Behind") across financial, universe; the assigned sub-agent is strictly con- legal, and academic domains in English and Chi- strainedtosearchtoolcallswithind , preventing i nese. Itspansfourtasktypeswithcontextlengths cross-documentdistractorchunksfromdegrading from 10K to over 250K tokens, and even strong local extraction. Each sub-agent receives the frontier models achieve only modest Avg Scores originalqueryq,itsassigneddocumentname,and andmediumperfect-answerrates,underscoringthe thesharedinstructionset(todolist),thenoperates difficultyofreasoningovermanylong,all-relevant in an iterative retrieve-and-reason loop. On each documents. turn, the agent either issues a search action (a Complementarydatasetsprobeotheraspectsof focused query string) or a finalize action that multi-document reasoning. MoNaCo (Wolfson terminates the loop and emits the document- et al., 2025) focuses on natural questions over groundedfindings. Thesub-agentpromptinstructs dozensofWikipediapages,MEBench(Linetal., the agent to attempt at least 2 focused searches 2025)onhigh-entity-densityQA,FanOutQA(Zhu before concluding a piece of information is et al., 2024) on multi-hop questions with absent, with a total cap of 5 search calls across long cross-document evidence chains, and all tasks. Each search action triggers dense HoloBench (Maekawa et al., 2024) on database- vector retrieval over the sub-agent’s dedicated style aggregation over unstructured text. Taken per-documentQdrantindex. ThisretrievalusesCo- together, these benchmarks show that scalable hereembed-v4.0embeddings(1536-dimensional, multi-document reasoning remains an open cosine similarity) to fetch the top k = 15 most challenge,withLoongemphasizingtheespecially similar chunks. These chunks are then re-ranked demandingall-relevant,long-contextregime. byCoherererank-v4.0-fasttoyieldafinalset

Figure1: OverviewofSPD-RAGArchitecture.
of top_n = 5 chunks per search. The documents Similarity-Ordered Merge & Synthesis.
t,
are split into chunks offline using LangChain’s In iteration we maintain a set of find-
RecursiveCharacterTextSplitter in Mark- ings/summaries S(t) = {s (t) ,...,s (t) }. We
1 n
--- --- --- --- --- --- --- --- --- --- --- --- --- ---
downmodewithachunksizeof1000tokensand embed each summary using Cohere embed-v4.0
250-tokenoverlap. and compute a cosine-similarity matrix via
----------------- --- --- --- --- --- --- ----------- --- ------------------- --- --- ------ ---
sklearn.metrics.pairwise.cosine_similarity.
FindingsOutput. Wedenotethefindingsofeach
--------------- --- --- ------------------------- --- --- --- ---- ------------ --- ---- -------- ------ ---
This is converted to a distance matrix
sub-agentas
(t) (t)
--- --- --- --- --- --- --- --- --- ----- ------- ----- --------- ---
D = 1 − cos(s ,s ), which is passed to
ij i j
o = α (q,d ) = ⟨s ,r ⟩ (1) AgglomerativeClustering with n_clusters=1,
i i i i i
----- ---- ----------- --- -------- -------- --- ----------------- --- --- -------- --- --------- ---
linkage="average" (UPGMA), producing a
where s is the natural language findings re-
i
completedendrogramoverallcurrentsummaries.
port from d and r ∈ [0,1] is a scalar rele-
---------------------- --- --- --------------------- -------- -------- ----- ------------ --- ----- ------------ ---------- -------- ---
i i
We traverse the merge tree bottom-up, greedily
vance/confidencescore. Theseoutputsarepassed
accumulating nodes into a batch as long as the
totheSynthesisLayer.
total tiktoken count does not exceed the target
------------ --- --- --- --------- --- ----- -------------- ---- --------- -------- ------ ------------ ---
Parallelism. All RAG loops for the docu-
budget of B = 750,000 tokens. Semantically
ments are dispatched concurrently via Lang- similarsummariesaregroupedfirst,soeachbatch
Graph’s Send API fan-out, which emits one contains the most similar available summaries
Send("document_sub_agent_node", ...) per
------------------------------- --- --- --- --- ---- --- --- --- --- --- --- --- ---
withinthetokenlimit.
documentandexecutesalltargetsinparallelwithin
LangGraph’sasyncruntime. AggregateandSynthesizeFindings. Foreach
batch,anLLMispromptedwiththeconcatenated
3.3 SynthesisLayer
findings, the synthesis directive, and the original
--- --- --- --- --- --- --- --------- ------------- --- ---------- --- ------------ ---
WhilemodernLLMsfeatureextensivecontextwin- queryq toproduceanaggregatedandsynthesized
dows,synthesizinghundredsofdocumentreports
summary. Allbatchsynthesiscallswithinanitera-
--- --- --- --- --- --- --- -------- ------------------------------------ --- --- --- --- ---
can still exceed these limits or cause ’lost in the tionareissuedconcurrentlyviaasyncio.gather.
middle’degradation. Tofuture-proofthearchitec- Themergedsummariesformtheinputforthenext
ture for massive corpora, the Synthesis Layer is
-------- ------- -------- --- ------------- ----- --- --------- ------- --- ---- --------- ------ ---
iteration S(t+1). The same SYNTHESIS prompt
designedasadynamicmap-reducepipelinethatag-
used at every level of the merging tree is ap-
--- --- --- --- --- --- --- ------- ----- ----- ------ ------- ------- ---
gregatesfindingsrecursively. TheSynthesisLayer plied even at the final level—there is no separate
receives the synthesis directives from the Coor- synthesis-onlyprompt.
dination Layer and the findings {o ,o ,...,o }
-------- ----- --- ------------ --- --------- --- --- --- --- --- --- --- ---
1 2 n
from the Parallel Retrieval Layer. It aggregates ContextSizeConditionandOutput. Thelayer
andsynthesizesthefindingsrecursivelythrougha evaluates whether the total findings size exceeds
similarity-orderedprocessuntilthetotalfindings the context size threshold (i.e., S(t+1) > 1). If
sizefallswithinthetargetcontextsizetoproduce theconditionistrue,theprocessloopsbacktothe
thefinaloutput. similarity-orderedmergeandsynthesisstep. Ifthe

Algorithm1RecursiveSynthesis Locating, Comparison, Clustering, or Chain of Reasoning,withcontextlengthsrangingfrom10K

Require: FindingsS = {s ,...,s },queryq,
1 n
to beyond 250K tokens. We evaluate on the En-
synthesisdirectived,contextsizebudgetB
Ensure: FinalOutputs⋆ glishandSet4(200k-250ktokens)portionofthe
benchmarkonly. Ourevaluationsetcomprises40
----------- ----- --- --- --- -------------- --- --------------------------- --- --- --- ---
1: while S > 1do
instancesinvolvingacademicpapersand62involv-
2: E ← COHEREEMBED(S)
---- ---------------- --- --- --- --- --- --- --- --- --- ---
D ← 1−COSINESIMILARITY(E) ingfinancialreports(102instancestotal),withthe
3:
tree ← AGGLOMERATIVECLUSTER( fourtasktypesdistributedas: SpotlightLocating
4:
(27),Comparison(15),Clustering(49),andChain
D, linkage = “average”)
--- ---------- ------------ --- --- --- --- --- --- --- --- ---
ofReasoning(11).
5: batches GROUPBYTOKENS(
---------- -------- -------------- --- --- --- --- --- --- --- --- ---
S, tree, B)
4.2 Baselines
6: if batches S then
-------------- --------- --------- --- --- --------------------- --- ------- --- --------- -------- ---
We compare against the following systems, all
7: batches ← [S]
endif backedbyGemini2.5Pro:
8:
9: S ← ASYNCGATHER(
---- ------------------- --- --- -------- ------------------------ --- --- --- --- --------------- ---
• Baseline(FullContext): Alldocumentsfor
SYNTHESIZE(b,q,d)∀b batches)
eachinstanceareconcatenatedandprovided
10: endwhile
directlyinthecontextwindowofGemini2.5
return S[0]
------ ---- --- --- --- --- --- --- --- --- --- ---
11:
Pro,representingtheoraclelong-contextup-
perbound.
conditionisfalse(thetotalfindingssizeiswithin
• NormalRAG:Standardvectorsearchtop-K
thecontextsize,leavingasinglefinalsummarys⋆),
retrieval over the full document corpus, fol-
----------- ---------- --------------------------- --- ------------ --------- --- ---- --------- -------- -------- ------------
the process terminates and yields s⋆ as the final
lowed by LLM reasoning over the retrieved
If S(t+1) S(t) (no-progresscase),the
output.
chunks.
entirecurrentlevelisforcedintoasinglebatchto
guaranteetermination.
• Agentic RAG: A single-agent ReAct-style
--- --- --- --- --- --------- --- ---- -------------- --- ----------- ---
Algorithm1givesthepseudocodeforthegeneral RAG system (implemented via Lang-
recursivesynthesisprocedure. Graph/LangChain) that can issue multiple
iterative retrieval calls over the full global
---------------- --- ------------------------ --- --- --------- --- --------- ----- ---- --- -----------
BehavioronLoong. Inpractice,withGemini2.5
Pro’s 1M-token context window and a budget of corpus. It uses the same embedding and
re-rankingpipelineas SPD-RAG,butlacks
--- --- --- --- --- -------------------- --- --- --- ---------------- --- ---
B = 750,000tokens,thecombinedsub-agentfind-
per-documentspecialization.
ingsforallinstancesinourLoongevaluationsetfit
withinasinglebatch,sotheconditionalcheckal-
4.3 EvaluationMetrics
lowedoutputafteroneiteration. Therecursiveloop
----------------------------- --- --- ---------------- --- --------- --- --------- --- -------- --------- ---
We report the following metrics, following the
isthereforeadesigncapabilityintendedformuch
Loongevaluationprotocol(Wangetal.,2024a):
largercorpora,wheretotalfindingssizegenuinely
exceedsthecontextsize.
• Avg Score: An LLM-judged score (0–100)
--- --- --- --- --- ----- ------ --- ---------- --- ----- -------
measuringthedegreetowhichthepredicted
4 ExperimentalSetup
answer accurately covers the gold answer,
--- --- --- --- --- ------ --- ---------- ------ --- -------- -------
4.1 Dataset
following the evaluation protocol of Loong
--- --- --- --- --- ------------------ --- --- ---------- -------- --- --------
(Wangetal.,2024a). 2
WeevaluateSPD-RAGontheLoongbenchmark
(Wangetal.,2024a). Loongisanextendedmulti-
------------------ ------------ ----------------------- ------- -------- ------------------- --- --- --- ------------------- --- ---
• PerfectRate(PR%): Percentageofqueries
document QA instances in both English and Chi-
wherethesystemreceivesaperfectscoreof
nese, with an average of 11 documents per test
---------- ---------- --------------- --- -------- --- --- --- --- --- --- ---
100.
casespanningtworeal-worldscenarios: financial
----------------------------------- --- --- --- --------- --- --- --- --- --- --- ---
reports and academic papers. Each test case is 2BecausetheoriginallegacyGPT-4modelAPIisunavail-
ablefornewscaledevaluations,weadoptGPT-5astheeval-
constructedsothateverydocumentisrelevantto
uator. Recent literature increasingly adopts GPT-5 as the
--- --- --- --- --- ------------- ---------- --- ------------ --- ------ ------------
the final answer ("Leave No Document Behind", standard for LLM-as-a-judge protocols due to its superior
meaningacorrectresponserequiressynthesizing alignmentwithhumangrading(Wolfsonetal.,2025).While
ourbaselinenumbersarere-computedunderthisGPT-5judge
evidencefromallprovideddocuments),andisan-
forstrictfairness,rawscoresmaynotbeperfectly1-to-1com-
notated under one of four task types: Spotlight parablewiththeoriginallypublishedLoongleaderboard.

• AvgTokenUsage: Meanper-querytotal(in- Cost tracking. Per-query costs are computed put+output)tokenusage. fromLangSmithrunmetadata(totaltokencounts ×per-tokenpricing.

• Avg Cost (USD): Mean per-query API cost,
enablingcost-efficiencycomparisons. 5 Results
5.1 MainResults
• AvgLatency(s): Meanper-querywall-clock
---------------- --- --- ----------------------- --- --- --- --- --- --- --- --- ---
time.
Table1reportsthemainresultsacrossallsystems
on our Loong evaluation set. Figure 2 illustrates
--- --- --- --- --- --- --- ------------ ---------- --- ---- ------ -------------
4.4 ImplementationDetails
theseperformancedifferencesacrossthefourspe-
AllsystemsuseGemini2.5Pro(temperature0.0) cifictasktypes.
----------------------------------------- --- --- --- --- --- --- --------------- --- --- --- --- ---
asthebackboneLLMforthecoordinator,merging SPD-RAGachievesanAvgScoreof58.1,sub-
layer, and synthesis layer. SPD-RAG document
---------- --------- --- ------ ------- --- -------- --- --- --- --- --- ---
stantiallyoutperformingbothNormalRAG(33.0)
sub-agents use Gemini 2.5 Flash for document-
---------- --- ------ --- ----- --- --------- ----------- --- ------- --- ---------------- ---
and Agentic RAG (32.8). This corresponds to
scopedretrieval,reducingper-documentcostwhile roughly a 25-point absolute improvement (about
preserving reasoning quality at the merging and 76% relative gain) over standard RAG baselines.
synthesisstages. GPT-5isusedexclusivelyasthe
---------------- --- --------------------------- --- --- --- --- ------------ ------- --- ---- ---- -----------
Furthermore, SPD-RAG more than doubles the
LLMjudgefortheevaluationoftheAvgscoreand Perfect Rate (PR) of Agentic RAG (18.6% vs.
is not part of the pipeline itself. Prompts for all 8.8%),indicatingthatexhaustivedocument-level
systems, including baselines, were optimized for
-------- --------- ---------- --- ---- --------- --- --- --- --- --- --- ---
processingmorefrequentlycapturesthecomplete
informationextractionandsynthesistoensurefair set of required facts. Notably, the Agentic RAG
comparison. Fullprompttemplatesforallsystems baseline,despiteconsuming∼3×moretokensthan
areprovidedinthecoderepository. NormalRAG,doesnotyieldscoreimprovements,
suggestingthatuninstructediterativeretrievalwith-
Indexing. Each document is pre-
--------- ---- --- --------- --- ------ ---- ---------------- --- -------------- --- ---- ----------
out per-document specialization does not effec-
indexed into a dedicated Qdrant vec-
tivelyaddressthecoveragechallengeinexhaustive
tor collection using LangChain’s
------------------------------ ---------- --- ----- --- ----------- ------- -------------- ------- ----------- ----- ------------ ------------
multi-document settings. While the full-context
RecursiveCharacterTextSplitter (Imple-
baseline attains the highest quality with an Avg
mentationdetailsareprovidedintheAppendix.).
Score of 68.0, SPD-RAG reaches 85.4% of this
--- --- --- --- --- --- --- -------- ----- ------- ------- ----- -------
Retrievalpersub-agent. Eachsearchtoolcall performancewhileconsumingonly37.9%ofthe
performs dense vector retrieval over the docu- API cost, demonstrating a highly favorable cost-
quality trade-off. The full-context baseline pro-
--------------------------- --- --- --- --- -------------- --- ------------------ --- --- ------------ -------- ----
mentindex,returningthetop-K (k = 15)chunks
using cosine similarity in Qdrant. These can- vides a strong upper bound that benefits from all
didates are subsequently re-ranked with Cohere documents in one pass. Despite this, SPD-RAG
narrowsthegapto9.9pointswhilecostingless.
rerank-v4.0-fast,andthetoptop_n = 5chunks
------------------------------- --- --- --- --- --- ------- --- --- --- --- --- ---
arepassedtothesub-agentLLM.
5.2 AnalysisbyTaskType
Merging layer. The token budget per merge
------- ------ --- ----- ------ --- --------- --- --- --- --- --- ---
Table2breaksdownperformancebyLoong’sfour
batchisB = 750,000tokens(75%ofGemini2.5
-------- ------------------------------ --- --- --- --- --- --- --- --- --- --- ---
tasktypes.
Pro’s1Mcontextcap). Agglomerativeclustering
------------------- --- --- ----------------------- --- --- --- --- --- --- --- --- ---
Thetask-typebreakdownrevealsaclearpattern.
usessklearnwithUPGMAlinkageandprecom-
For Spotlight Locating—which requires finding
--- --- --- --- --- --- --- ------------- -------------- --- --- -------- -------
putedcosine-distancematrix.
asinglesalientfactacrossdocuments—allRAG-
based systems perform reasonably well (69–74),
------------- --------------- ----------------------------- ----- --------- ----------- ---------- -------------------------------------------- ------------ ------- ---------- ----- -----------
Parallelism. Documentagentsrunconcurrently
while the full-context baseline leads (86.6). The
via LangGraph Send API fan-out. Batch synthe-
largest gaps between SPD-RAG and the RAG
sis calls within each merge iteration are paral-
asyncio.gather. baselinesappearinClustering(+40.5ptsoverNor-
lelized with Synchronous Co-
malRAG)andChainofReasoning(+26.2ptsover
hereAPIcallsareoffloadedtothethreadpoolvia
Agentic RAG), tasks that require aggregating or
--- --- --- --- --- --- --- ------------- --- ----- ------------ ----------- ---
asyncio.to_thread.
reasoningoverevidencefrommanydocumentssi-
Safety limits. Each document sub-agent’s iter- multaneously. Ontheotherhand,itnearlymatches
ative retrieval loop is capped at 5 iterations; the the full-context baseline (42.2 vs. 42.7) on Com-
AgenticRAGbaselinecapsat10iterations. parisontasks.
------------------------------------- --- --- --- --- --- --- ------------- --- --- --- --- ---

System AvgScore PR(%) AvgInputTok AvgTotalTok AvgCost($) AvgLatency(s) OracleLong-ContextBaseline

Baseline(FullContext) 68.0 31.4 253,085 255,345 0.273 45.6
RAGBaselines
NormalRAG 33.0 13.7 22,174 27,430 0.080 42.6
---------- --- ---- ----------- ------ ----- ----
AgenticRAG 32.8 8.8 81,877 85,290 0.098 40.6
OurSystem
SPD-RAG 58.1 18.6 193,954 205,683 0.103 54.8
------- --- ---- ------------ ------- ----- ----
Table1: MainresultsonourLoongevaluationset(102instances: 40academicpaper,62financialreport). Bold:
bestoverall. Underline: bestamongRAG-basedsystems.
------------ ---------- -------------------------- --- --- --- ---
Figure2: ComparisonofAverageScoreacrossthefoursystems,brokendownbytasktype(SpotlightLocating,
Comparison,Clustering,andChainofReasoning).
5.3 AnalysisbyDocumentDomain
As shown in Table 3 and Figure 3 the domain
-------- ---------- ---------- ------------ --- --- ---
breakdownexposesastrikingfailuremodeofstan-
dard RAG: both Normal RAG and Agentic RAG
--------- ----------- ------- ----------- --- --- ---
achieve0%PRonacademicpaperinstances(Avg
Scoresof15.2and16.8,respectively). Academic
---------------------------------- --- --- -------- --- --- ---
paperinstancesinLoongtendtoinvolvelong,tech-
nicaldocumentswithdistributedevidence,making
top-K retrievalespeciallysusceptibletocoverage
failures. SPD-RAGdramaticallyrecoversonthis
domain(60.0AvgScore),closingmostofthegap
with the full-context baseline (78.8). On finan-
-------- ------------ ---------------- --------- --- --- ---
Figure3: Averagescorebydocumentdomaincompar-
cialreportinstances—whichtendtobeshorterand ingtheBaseline(FullContext),NormalRAG,Agentic
morestructured—allRAG-basedsystemsperform
RAG,andSPD-RAGsystems.
better,andthegapbetweenSPD-RAG(56.9)and
thebaseline(61.0)issmaller.
System SpotlightLoc. Comparison Clustering ChainofReasoning
(n=27) (n=15) (n=49) (n=11)
Baseline(FullContext) 86.6/55.6% 42.7/26.7% 67.1/14.3% 60.9/54.5%
NormalRAG 69.7/37.0% 37.7/26.7% 15.4/0.0% 14.8/0.0%
--- ---------- --- ---------- --- ---------- --------- --- ---------- --- --- ---
AgenticRAG 73.4/22.2% 23.3/20.0% 16.7/0.0% 17.9/0.0%
SPD-RAG 74.2/44.4% 42.2/20.0% 57.2/4.1% 44.1/18.2%
Table2: AvgScore/PR(%)byLoongtasktype. EachcellshowsAvgScore/PR%.
Crucially, thearchitectureof SPD-RAG enables
-------- --- ----------- --------------- --- ---------- ----------------- --- --------------- ------- --------- -------
System Paper(n=40) Financial(n=62)
this cost efficiency: by constraining retrieval to
Baseline 78.8/30.0% 61.0/32.3%
NormalRAG 15.2/0.0% 44.5/22.6% isolated,single-documentspaces,wecanreliably
AgenticRAG 16.8/0.0% 43.1/14.5%
---------- --- --------- ---------- --- --- --- --- --- --- --- ---
offloadtheiterativereasoningtoacheapermodel
SPD-RAG 60.0/7.5% 56.9/25.8%
------- --- --------- ---------- --- ------- ----------- --- ------------ --- ------ ---------
(Gemini 2.5 Flash). In contrast, global iterative
baselinesrequirethereasoningcapacityofafron-
Table3: AvgScore/PR(%)bydocumentdomain.
tier model (Gemini 2.5 Pro) to navigate the fully
--- --- --- --- --- ---- ------------- --- ---- ----------- --- ---------
concatenatedcorpus,drivingupcosts.
System AvgScore AvgCost($) Score/$
---------- --- -------- ---------- ------- ------------------- ---------- --- ---- ------------------- --- ---------
Baseline 68.0 0.273 249.1
NormalRAG 33.0 0.080 412.5 6 Discussion
AgenticRAG 32.8 0.098 334.7
SPD-RAG 58.1 0.103 564.1
WhereSPD-RAGexcels. Thetask-typeresults
in Table 2 confirm our core hypothesis: architec-
Table4: Cost–qualitytradeoff.
turaldecompositionalongthedocumentaxisyields
the largest gains precisely for tasks that require
--- --- --- --- --- ----------- -------------- --------- --- ---------- ---------- -------
exhaustive multi-document synthesis. Clustering
5.4 Cost–QualityTradeoff
tasks(+40.5overNormalRAG)andChainofRea-
soning tasks (+26.2 over Agentic RAG) both de-
--- --- --- --- --- ------ ------------ ---- ------- --- ---- --------
mandthatthesystemformacoherentanswerfrom
evidencedistributedacrossallrelevantdocuments—
exactlythescenarioforwhichper-documentagents
aredesigned. ForLoong’sComparisonquestions,
--- --- --- --- --- ------------ ------------------------------ --- --- --- --- ---
theanswerisprimarilydeterminedbyreadingout
asmallsetofcomparablenumericattributesfrom
each report and aggregating them, so once docu-
--- --- --- --- --- -------- -------------- ----------- --------- ----- ------------ --------
ment agents have extracted those fields, the syn-
thesizer is effectively operating over a structured
table,whichhelpsexplainwhySPD-RAG’sscore
onComparisontasks(42.2)nearlymatchesthefull-
Figure4: Cost–Qualitytradeoff. Thescatterplotillus- contextbaseline(42.7).
tratestheParetofrontierformulti-documentQA.
Remaining gap with the full-context baseline.
--- --- --- --- --- --------- --- ---- --- ------------ --- ---------
SPD-RAG outperforms the RAG baselines in Despite strong gains over RAG baselines, SPD-
the cost–quality trade-off. It achieves a 76% RAG lags the full-context baseline by 9.9 Avg
higheraveragescorethanNormalRAG(58.1vs. Score points overall. Three factors likely con-
33.0)whileincreasingtheper-querycostbyonly tribute: (1) Gemini 2.5 Flash, used for document
$0.023 (Table 4). In contrast, Agentic RAG is agents due to its cost efficiency, may provide
Pareto-dominated, as it incurs higher cost than weaker agentic reasoning capabilities compared
NormalRAG($0.098vs.$0.080)whiledelivering to larger models. (2) The coordinator’s sub-task
nearlyidenticalquality(32.8vs.33.0). Compared generation may under-specify queries for highly
tothefull-contextbaseline,whichachievesanAvg technical academic content, leading to incom-
Score of 68.0, SPD-RAG reaches 85.4% of the pleteinformationextractionatthedocument-agent
qualityatonly37.9%ofthecost, resultingina level. (3) The maximum context length observed
2.25× improvement in cost–quality efficiency. inLoongquerieswasapproximately250ktokens—

onlyabout25%ofthe1M-tokencontextwindow onthecoordinator’sabilitytogeneratecomprehen- of Gemini 2.5 Pro—potentially limiting the pres- sivesub-tasks: under-specifiedtasksleadtoincom- sureonthefull-contextbaseline. SinceSPD-RAG plete document-level extractions, as observed on isdesignedtooperateonsubstantiallylargercon- technicalacademicpaperinstances. Ourevaluation texts,itsadvantagesmaybecomemorepronounced islimitedtotwodomains(academicpapersandfi- undermoreextremelong-contextconditions. nancialreports)fromtheLoongbenchmark;legal, medical,orenterprisedocumentcorporamayhave

RAG baseline failure on papers. The 0% PR
differentstructuralcharacteristicsthatalterrelative
rate and 15.2-16.8% Avg Score of both Normal
-------- ---------- --- --------- --- ----------- --- --- --- --- --- --- ---
performance.
RAG and Agentic RAG on academic paper in-
------- ------- --- --- -------- ----- --- --- --- --- --- --- ---
ThesynthesislayerofSPD-RAGisdesignedto
top-K
stances highlights a systematic failure of
------- ---------- ------------ --- ------- --- --- --- --- --- --- --- ---
handlecorporawherethecombinedsub-agentout-
retrieval under dense, distributed evidence. Aca-
--------- ----- ------ ----------- --------- --- ---- --- --- --- --- --- ---
putsexceedthemodel’scontextwindow,triggering
demic papers in Loong often require synthesiz-
----- ------ -------- ----- ------- ---------- --- --- --- --- --- --- ---
multi-roundsimilarity-basedclusteringandrecur-
ingfactsspreadacrossabstracts,methods,results,
sive synthesis. In our Loong experiments, how-
--- --- --- --- --- --- --- --------------- --- ------------ ------------ --- ----
andappendicesofmultipledocuments—aregime
ever,Gemini2.5Pro’s1M-tokencontextwassuffi-
where exhaustive per-document coverage proves
---------------- --- ------------ --- -------- ------ --- --- --- --- --- --- ---
cienttoprocessallsub-agentsummariesinasingle
highly effective. The recovery by SPD-RAG to
------ ---------- --- -------- ---------- --- --- ----------- --- -------------- ---- --- -----------
merge step, so this recursive path was never acti-
60.0AvgScore/7.5%PRinthisdomaindemon-
vated. Asaresult,thescalabilitypropertiesofthe
--- --- --- --- --- --- --- ---------------------------------------------- --- --- --- --- ---
stratesthepracticalvalueofper-documentspecial-
recursivesynthesispipeline—itsimpactonanswer
ization.
quality, redundancy reduction, and cost as docu-
--- --- --- --- --- --- --- -------- ---------- ---------- --- -------- --------
Latencyoverhead. SPD-RAG incursamodest mentcountsgrowintothehundredsorthousands—
latency overhead (54.8 s vs. 40.6–45.6 s for the remainempiricallyunvalidated. EvaluatingSPD-
baselines), primarily due to its multi-agent archi-
----------- --------- --- ------ --------------- --- ------ --- --- --- --- --- ---
RAGonmuchlargercorpora,andideallyonanew
tecture. Although document agents run in paral- benchmarkspecificallytargetinghundredstothou-
lel,end-to-endlatencyisstillgatedbythelayered sands of documents per query instance, is an im-
pipeline, which requires at least three sequential portantdirectionforfutureworkthatwouldmore
LLM calls (coordination, per-document retrieval, directlytesttheper-documentagentdesignandthe
andsynthesis)ratherthanasinglepass. intendedlarge-databaseregime.
8 Conclusion
--- --- --- --- --- --- --- -------------------------- --- -------- ---------------- ---------- ------
We presented SPD-RAG, a hierarchical multi-
agent framework designed for exhaustive multi-
documentquestionanswering. Byassigningaded-
icatedagenticRAGmoduletoeachdocumentand
mergingtheirfindingsthroughasimilarity-ordered,
token-bounded tree, our system effectively miti-
--- --- --- --- --- --- --- ----------------------------------------- ---------- --------- --------- ----------- ----------
gatesthelimitationsofbothtraditionaltop-K re-
trieval (incomplete coverage) and isolated long-
context processing (degraded reasoning at scale).
Figure5: Averageper-querylatencyacrosssystems. ExperimentsonthechallengingLoongbenchmark
demonstratethatSPD-RAGachievesanaverage
scoreof58.1,outperformingNormalRAG(33.0)
7 LimitationsandFutureWork
andAgenticRAG(32.8)byapproximately25ab-
SPD-RAG incurs higher per-query LLM call solute points (76% higher average score), while
countsthansingle-passsystems—onecallperdoc- operating at only 37.9% of the API cost of the
ument agent plus a final synthesis step—which oracle full-context baseline (68.0). These per-
increasestotaltokenusagecomparedtostandard formance gains are most pronounced in tasks re-
RAGbaselines,thoughitremainsatroughlyone- quiring deep cross-document synthesis—such as
thirdthecostofthefull-contextbaseline($0.10vs. Clustering(+40.5points)andChainofReasoning
$0.27perquery)duetotheuseofGemini2.5Flash (+26.2points)—aswellasondenseacademicpa-
fordocumentsub-agents. Systemqualitydepends perswherestandardRAGmethodsentirelyfail.

Ultimately, our findings demonstrate that for TaichengGuo,XiuyingChen,YaqiWang,RuidiChang, complex information-seeking queries over large ShichaoPei,NiteshV.Chawla,OlafWiest,andXi-

angliangZhang.2024. Largelanguagemodel-based
corpora, how information is processed is crucial.
multi-agents: Asurveyofprogressandchallenges.
Specifically,ensuringthateachdocumentreceives
Preprint,arXiv:2402.01680. ArXiv:2402.01680.
--- --- --- --- --- --- --- -------------------------- --- --- ----------------- --- ---
exhaustive,dedicatedagenticattentionprovestobe
Siwei Han, Peng Xia, Ruiyi Zhang, Tong Sun, Yun
--- --- --- --- --- --- --- ---------- ---- ---------- ------ ---- --------
amoreeffective,cost-efficient,andscalablestrat-
Li, Hongtu Zhu, and Huaxiu Yao. 2025. MDocA-
--- --- --- --- --- --- --- ---------- ---- --- ----------- ----- ------
egythansimplyexpandinghowmuchrawcontext
gent: Amulti-modalmulti-agentframeworkfordoc-
asinglemodelcanconsumeinonepass. umentunderstanding. Preprint,arXiv:2503.13964.
ArXiv:2503.13964.
9 EthicsStatement
Yubin Kim, Ken Gu, Chanwoo Park, Chunjong Park,
--- --- --- --- --- --- --- ---------- --- ----------- ----- -------- -----
SPD-RAG is a retrieval-augmented generation SamuelSchmidgall,A.AliHeydari,YaoYan,Zhi-
hanZhang,YuchenZhuang,MarkMalhotra,PaulPu
framework intended to improve access to infor-
--------- -------- --- ---------- ------ --- --------- --- --- --- --- --- ---
Liang,HaeWonPark,YuzheYang,XuhaiXu,Yilun
mation distributed across large document collec-
------ ----------- ------ --- -------------- --- ------- ----------- --- ---------- -------- ------ -------
Du, Shwetak Patel, Tim Althoff, Daniel McDuff,
tions. ThesystemreliesoncommercialLLMAPIs and Xin Liu. 2025. Towards a science of scal-
(Gemini2.5,Cohere),andaswithanyLLM-based ing agent systems. Preprint, arXiv:2512.08296.
ArXiv:2512.08296.
pipeline, outputs may contain factual errors and
--------- ------- --- ------- ------- ------ --- --- --- --- --- --- ---
should not be treated as authoritative without hu- PatrickLewis,EthanPerez,AleksandraPiktus,Fabio
man verification. The increased number of API Petroni,VladimirKarpukhin,NamanGoyal,Hein-
richKüttler, MikeLewis, Wen-tauYih, TimRock-
--------- ------ -------- ------------ ----------- ------- --------- ------------------- --------- ---------- ----------- ----- ------------
calls per query relative to single-pass systems re-
täschel, Sebastian Riedel, and Douwe Kiela. 2020.
sults in higher energy consumption, a cost that
Retrieval-augmented generation for knowledge-
should be weighed against the accuracy gains in intensiveNLPtasks. InAdvancesinNeuralInforma-
deploymentdecisions. Ourbenchmarkevaluations tionProcessingSystems.
are conducted on publicly available datasets and
------------- --- ----------- --- --------- -------- --- -------- -------- ------------- --- ------------- ---
TengLin, YuyuLuo, HonglinZhang, JichengZhang,
involvenohumansubjectsorpersonaldata. Dur- Chunlin Liu, Kaishun Wu, and Nan Tang. 2025.
ingthepreparationofthismanuscript,AI-assisted MEBench: Benchmarkinglargelanguagemodelsfor
cross-documentmulti-entityquestionanswering. In
--- --- --- --- --- --- --- -------------------------------------------- --- --- --- --- ---
writingtoolswereusedtohelprefinelanguageand
ProceedingsoftheConferenceonEmpiricalMethods
improveclarity. Allresearchdesign,experiments,
--------------- --- ------------------------------ --- --- --- --- --- --- --- --- --- ---
inNaturalLanguageProcessing(EMNLP).
analysis,andfinaldecisionsregardingthecontent
NelsonF.Liu,KevinLin,JohnHewitt,AshwinParan-
wereconductedandverifiedbytheauthors.
jape,MicheleBevilacqua,FabioPetroni,andPercy
Liang.2023. Lostinthemiddle: Howlanguagemod-
--- --- --- --- --- --- --- ------------------- --- ---------------------------- --- --------------- ---
elsuselongcontexts. TransactionsoftheAssociation
References
forComputationalLinguistics,12.
Haonan Bian. 2025. LLM-empowered knowl-
------ ----- ----- ------------- --- --- ------ --- --- --- --- --- ---
SeijiMaekawa,HayateIso,andNikitaBhutani.2024.
edge graph construction: A survey. Preprint,
----------------- ----- ------------- ----------------- --------- --- --------- ------------------------------------- --- --- --- --- -------
Holisticreasoningwithlong-contextLMs: Abench-
arXiv:2510.20345. ArXiv:2510.20345.
markfordatabaseoperationsonmassivetextualdata.
Darren Edge, Ha Trinh, Newman Cheng, Joshua Preprint,arXiv:2410.11996. ArXiv:2410.11996.
Bradley, Alex Chao, Apurva Mody, Steven
-------- ---- ----- --- ------ ----- ------ -------- ------ ----- ---------- --- ------------
David J. Moore. 2025. A taxonomy of hierarchical
Truitt, Dasha Metropolitansky, Robert Osazuwa multi-agentsystems: Designpatterns,coordination
Ness, and Jonathan Larson. 2024. From lo-
--------------------- ------- -------- -------------------------- -------- --- --------- ----------------- --- ----------------- ------------- --- ---------
mechanisms, and industrial applications. Preprint,
cal to global: A graph RAG approach to query-
arXiv:2508.12683. ArXiv:2508.12683.
focusedsummarization. Preprint,arXiv:2404.16130.
ArXiv:2404.16130.
LituOuandMirellaLapata.2025. Context-awarehier-
--- --- --- --- --- --- --- ---------------------------- --- --- --- ------------------ ---
archicalmergingforlongdocumentsummarization.
Gemini Team, Petko Georgiev, Ving Ian Lei, Ryan
-------- ----- ----- --------- ------- -------- ------- -------------------------- --- --- ----------------- --- ---
Preprint,arXiv:2502.00977. ArXiv:2502.00977.
Burnell, Libin Bai, Anmol Gulati, Garrett Tanzer,
DamienVincent,ZhufengPan,ShiboWang,and1 Parth Sarthi, Salman Abdullah, Aditi Tuli, Shubh
others. 2024. Gemini 1.5: Unlocking multimodal Khanna, Anna Goldie, and Christopher D. Man-
understandingacrossmillionsoftokensofcontext. ning. 2024. RAPTOR: Recursive abstractive pro-
Preprint,arXiv:2403.05530. ArXiv:2403.05530. cessing for tree-organized retrieval. Preprint,
arXiv:2401.18059. ArXiv:2401.18059.
---------- ------ --- ------- ------- ----- --- ----------------- --- ----------------- --- --- ---
Jiani Guo, Zuchao Li, Jie Wu, Qianren Wang, Yun
Li, Lefei Zhang, Hai Zhao, and Yujiu Yang. 2025. LiSun,LiuHe,ShuyueJia,YangfanHe,andChenyu
ToM:Leveragingtree-orientedMapReduceforlong- You. 2025. DocAgent: An agentic framework for
contextreasoninginlargelanguagemodels. InPro- multi-modallong-contextdocumentunderstanding.
ceedingsoftheConferenceonEmpiricalMethodsin InProceedingsoftheConferenceonEmpiricalMeth-
NaturalLanguageProcessing(EMNLP). odsinNaturalLanguageProcessing(EMNLP).

V.A.Traag,L.Waltman,andN.J.vanEck.2019. From extraction tasks and write a synthesis louvaintoleiden: Guaranteeingwell-connectedcom- directive to guide the downstream

munities. ScientificReports,9(1):5233. synthesizer.
2. Sub-agents (next) Each document
Minzheng Wang, Longze Chen, Cheng Fu, Shengyi is assigned one worker that runs your
Liao,XinghuaZhang,BingliWu,HaiyangYu,Nan tasks independently. Workers search
Xu,LeiZhang,RunLuo,YunshuiLi,MinYang,Fei their document and report raw findings.
They run in parallel and cannot see each
------------------------- --- --- --- --------------- --- --- -------- ----------- --- --- ------ --------
Huang,andYongbinLi.2024a. Leavenodocument
other’s results.
behind: Benchmarkinglong-contextLLMswithex-
------------------ ----------------------------------- --- -------------------------- --- --- --- -------------- -------- ------ ------ ------------ --------
3. Synthesizer (last) A downstream
tendedmulti-docQA. Preprint,arXiv:2406.17419.
agent receives ALL worker findings
ArXiv:2406.17419.
and merges them into a single
---------- ------ --- ----- -------- ----- ------ ------------------- --------- ---- --------- ------- -------
coherent response. It follows your
Qian Wang, Tianyu Wang, Zhenheng Tang, Qinbin
synthesis_directive to decide what to
Li,NuoChen,JingshengLiang,andBingshengHe.
prioritize and how to structure the
------ ---------- --- -------------------------- --- --- --- ---------- --- --- --- --------- ---
2024b. Megaagent: Alarge-scaleautonomousLLM-
output.
basedmulti-agentsystemwithoutpredefinedSOPs.
You CANNOT see the names, types, or
-------------------------- --- --- --- ----------------- --- --- ---------- ------ ---------- ------ ------ ---
Preprint,arXiv:2408.09955. ArXiv:2408.09955.
content of the documents.
TomerWolfson,HarshTrivedi,MorGeva,YoavGold- Your ONLY job in this step:
berg, Dan Roth, Tushar Khot, Ashish Sabharwal,
------------------ --------- ------ -------------------------- ------- --------- ---------- ---------- ---------- ---------------------- ----------- -------------- -------
• Produce a list of subagent_todos
and Reut Tsarfaty. 2025. Monaco: More nat-
(as structured output): precise
ural and complex questions for reasoning across
extraction tasks that will be
dozensofdocuments. Preprint,arXiv:2508.11133.
executed independently against EACH
ArXiv:2508.11133. document by the sub-agents.
• Produce a synthesis_directive: a
Wentao Zhang, Liang Zeng, Yuzhen Xiao, Yong- concise instruction (2–4 sentences)
cong Li, Ce Cui, Yilei Zhao, Rui Hu, Yang Liu, for the synthesizer.
Yahui Zhou, and Bo An. 2025. AgentOrchestra:
----- ----- ------ --- ----- --------------- --- --- --- --- --- --- ---
A hierarchical multi-agent framework for general- Todo-writing rules:
purpose task solving. Preprint, arXiv:2506.12508.
----------------- ---- -------- --------- ----------------- --- --- ----------- --- ----------- ---- ------------- ----
• Decompose the user query into
ArXiv:2506.12508. concrete information requirements.
Jun Zhao, Can Zu, Hao Xu, Yi Lu, Wei He, Yiwen • Each todo must be self-contained
and unambiguous.
Ding, Tao Gui, Qi Zhang, and Xuanjing Huang.
----- ---------- --- --------------------------- --- -------- ------ -------- --- ------ ----- ---- -----
• Prefer atomic tasks over broad
2024. LongAgent: Scalinglanguagemodelsto128k
tasks.
contextthroughmulti-agentcollaboration. Preprint,
--------------------------------------- ----- --- ----------------- ----- ---- --------- --------- --- --------------- ------------ ------------ --------
• Include coverage for: definitions,
arXiv:2402.11550. ArXiv:2402.11550.
numeric values, constraints, edge
cases, error modes, and any
Zihan Zhou, Chong Li, Xinyi Chen, Shuo Wang,
explicit recommendations required
YuChao,ZhiliLi,HaoyuWang,QiShi,ZhixingTan,
by the user query.
--- --- --- --- --- --- --- --- -------- ------ --- --- ---
XuHan,XiaodongShi,ZhiyuanLiu,andMaosong
• Design a robust extraction list
---------- ---------- -------------- ----- ----- ---------- ------- -------- ----- ------ ------------ --- ------
Sun. 2025. LLM×MapReduce: Simplified long-
that works for ANY document in the
sequence processing using large language models.
set.
InProceedingsoftheAnnualMeetingoftheAssocia-
tionforComputationalLinguistics(ACL). Important Constraints:
---------------------------------------- --- ----- --------- --- --- ---------- --------- ------------ ----- -------- ------- --------
Do not assume any document contains
AndrewZhu,AlyssaHwang,LiamDugan,andChris
the answer. Write todos that can
Callison-Burch. 2024. FanOutQA: A multi-hop,
be answered with either “Found” or
multi-documentquestionansweringbenchmarkfor
“Not found in this document.”
-------------- --- ------- --- ----------- --- ---------- ------ ----- ------ --------------- ----------- ---
large language models. In Proceedings of the An-
• Tell the worker WHAT to extract, not
nualMeetingoftheAssociationforComputational
HOW to extract it.
--- --- --- --- --- --- --- --- ---------- --- --- --- ---
Linguistics(ACL).
• Do not synthesize, summarize, or
--- --- --- --- --- --- --- ------- --- ----------- --- ---------- -----
attempt to answer the user query
A Prompts
yourself.
All prompts are defined in
--- ------- --- --- --- ------- --- --- --- --- --- --- ---
A.2DocumentSub-AgentPrompt
backend/core/prompts.py.
(RESEARCH_SYSTEM_PROMPT)
A.1CoordinatorPrompt You are a sub-agent investigating a
------------------------ --- --- --- --- --- --- ---------------- ----------- ------------ ------------- --- ---
(LEAD_RESEARCHER_PROMPT) single document: {file_name}.
You are a lead researcher coordinating You operate inside an iterative
a RAG-based analysis to answer a user retrieval loop. On each turn you output
query. exactly one structured action:
-------- --- ------------- --- --- --- --- ------------------ -------------- --- ------- --- -------
Pipeline Architecture: • action="search": Issue a focused
  1. YOU (now) — Decompose the query into query to retrieve information from

the document. Set query to a • Follow the synthesis directive specific, targeted search string. above — it defines your main goal, Set reasoning to why this query is priorities, and output structure.

needed. Keep only information that directly
• action="finalize": You have helps answer the query. Discard
gathered sufficient evidence to tangential content.
--- -------- --- ---------- -------- ---------- --- --- ------------ ------------ -------- ------ ------
address ALL assigned tasks. Set
Preserve exact numbers, names,
findings to your complete extracted
dates, and caveats.
report. Set reasoning to a brief
Remove redundancy. If the same
summary of what you found.
fact appears multiple times, keep
it once.
Investigation principles:
--- ------------- -------------- ---- ----- --------- --- --- ------- -------- --------- ----- --------
Do NOT invent or infer facts not
present in the findings.
1. Start by identifying the key facts
required for each task. Same language as the findings
2. Issue ONE focused query per turn (default English if mixed).
— prefer specific terms over broad
--- --------- -------- -------- ----- ----------- --- --------------------- --- --- --- --- ---
phrases. B ImplementationDetails
3. Expand to synonyms or paraphrases
Models.
if initial results are incomplete. The coordinator, the merging layer,
4. Issue separate queries for and the synthesis layer use gemini-2.5-pro
different aspects of a task.
--- --------- --------- ------- ----- ------- ------------ --- ----- --- -------- --- ----------
(temperature 0.0). Document sub-agents
5. Keep searching until every task is
covered with concrete evidence or use gemini-2.5-flash (temperature 0.0) for
confirmed absent. document-scoped retrieval. The LLM judge
--- --------- --- ------- --- --- --------------- --- --- ---------- --- --- ---------
6. Do NOT attempt to answer the user (GPT-5) is separate and is used only for the
query directly extract raw facts
--- ----- -------- --- ------- --------- ------------------------ --- --- --- ----------------- --- ---
evaluationoftheAvgscore. Modelconstantsare
only.
definedinbackend/shared/constants.py.
7. Do NOT finalize a task as ’Not
--- ----------------- ------------ ------------ ---------- ----------- ----------------------------- --- --- --- ------------------------- --- -----------
found’ after only a single focused
search. At least attempt 2 Hyperparameters.
focused searches before concluding
information is absent.
Parameter Value
8. Do NOT focus on very specific terms,
Chunksize(tokens) 1000
but rather on the general context
Chunkoverlap(tokens) 250
of the task. Always try to find the
Tokenizer tiktoken cl100k_base
most relevant information.
Embeddingmodel Cohereembed-v4.0
9. You must use AT MOST 5 searches to
Embeddingdimension 1536
answer a task. DO NOT OVERUSE THE
Similaritymetric Cosine
SEARCH TOOL.
MergetokenbudgetB 750,000tokens
Denseretrievaltop-K 15
Finalize report format: For each
Reranker Coherererank-v4.0-fast
assigned task, output either “Found:
Rerankertop-N 5
[exact answer with supporting evidence]”
Sub-agentiterationsafetylimit 5
or “Not found in this document.” Always
Clusteringalgorithm Agglomerative(UPGMA)
report exact numbers, names, and dates.
Clusteringmetric Precomputedcosinedistance
Never approximate or infer beyond the
document.
Cost measurement. Per-query costs
--- --- --- --- --- --- ---- ------ ------------ --------- --------- --- --------
are pulled from LangSmith run metadata
A.3Merge/SynthesisPrompt
(SYNTHESIS_PROMPT) (extract_langsmith_info.py) using model-
------------------ --- --- --- --- --- --------------------------- --- --- --- --- ----- ------
specificper-tokenpricing.
Thispromptisuseduniformlyateverylevelofthe
recursivemergingtree,includingthefinalsynthesis
step. Thereisnoseparatefinal-answerprompt.
You are a research synthesizer. Merge
--- ------------- ----------------- ------------ -------- -------- --- --- --- --- --- --- ---
the following sub-agent findings into
one compact, information-dense response
for the user.
Query: {query }
Synthesis Directive:
{synthesis_directive}
Findings Batch: {findings }
--- -------- ------ --------- --- --- --- --- --- --- --- --- ---
Rules: