docs/bugs/P0_MCP_TOOLUSECONTENT_MISSING.md

P0 Bug: mcp.types.ToolUseContent AttributeError on HuggingFace Spaces

Status: FIXED Severity: P0 (App completely broken) Discovered: 2025-12-04 Fixed: 2025-12-04 (PR TBD)

---

Symptom

HuggingFace Spaces deployment crashes with:

module 'mcp.types' has no attribute 'ToolUseContent'

The app fails to start entirely. No functionality works.

---

Root Cause

Dependency version mismatch between pyproject.toml and requirements.txt.

File	MCP Pin	Result
pyproject.toml	mcp>=1.23.0	Correct - has ToolUseContent
requirements.txt	(missing)	Pulls old MCP via gradio[mcp] transitive dep

Background:

• ToolUseContent was added in MCP spec 2025-11-25 via SEP-1577 (Sampling With Tools)
• Our pyproject.toml correctly pins mcp>=1.23.0 (for security fix GHSA-9h52-p55h-vw2f)
• HuggingFace Spaces uses requirements.txt, NOT pyproject.toml
• gradio[mcp]>=6.0.0 pulls in MCP as transitive dependency
• Without explicit pin, Gradio was pulling an older MCP version lacking ToolUseContent

---

Fix

Added explicit MCP pin to requirements.txt:

# UI (Gradio with MCP server support - 6.0 required for css in launch())
gradio[mcp]>=6.0.0
+
+# Security: Pin mcp to fix GHSA-9h52-p55h-vw2f and ensure ToolUseContent exists
+mcp>=1.23.0

Also synced ALL dependencies between pyproject.toml and requirements.txt to prevent future drift.

---

Changes Made

Files modified:

• requirements.txt - Full sync with pyproject.toml:
  • Added mcp>=1.23.0 (root cause fix)
  • Added beautifulsoup4>=4.12 (was missing)
  • Fixed huggingface-hub>=0.24.0 (was 0.20.0)
  • Added upper bound to agent-framework-core>=1.0.0b251120,<2.0.0
  • Added sync header comment with date

---

Prevention

1. Sync header: requirements.txt now has "Last synced: YYYY-MM-DD" comment
2. CI check: Consider adding a pre-commit hook to validate requirements.txt matches pyproject.toml

---

References

• MCP Python SDK Releases
• MCP Spec 2025-11-25 - Sampling With Tools
• GHSA-9h52-p55h-vw2f - MCP security advisory

---

Verification

After fix:

1. Deploy to HuggingFace Spaces
2. Verify app starts without errors
3. Verify MCP server responds at /gradio_api/mcp/