File size: 4,930 Bytes
0dbc9de | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 | ---
title: Custom Tools
description: Create tools the LLM can call in opencode.
---
Custom tools are functions you create that the LLM can call during conversations. They work alongside opencode's [built-in tools](/docs/tools) like `read`, `write`, and `bash`.
---
## Creating a tool
Tools are defined as **TypeScript** or **JavaScript** files. However, the tool definition can invoke scripts written in **any language** — TypeScript or JavaScript is only used for the tool definition itself.
---
### Location
They can be defined:
- Locally by placing them in the `.opencode/tools/` directory of your project.
- Or globally, by placing them in `~/.config/opencode/tools/`.
---
### Structure
The easiest way to create tools is using the `tool()` helper which provides type-safety and validation.
```ts title=".opencode/tools/database.ts" {1}
import { tool } from "@opencode-ai/plugin"
export default tool({
description: "Query the project database",
args: {
query: tool.schema.string().describe("SQL query to execute"),
},
async execute(args) {
// Your database logic here
return `Executed query: ${args.query}`
},
})
```
The **filename** becomes the **tool name**. The above creates a `database` tool.
---
#### Multiple tools per file
You can also export multiple tools from a single file. Each export becomes **a separate tool** with the name **`<filename>_<exportname>`**:
```ts title=".opencode/tools/math.ts"
import { tool } from "@opencode-ai/plugin"
export const add = tool({
description: "Add two numbers",
args: {
a: tool.schema.number().describe("First number"),
b: tool.schema.number().describe("Second number"),
},
async execute(args) {
return (args.a + args.b).toString()
},
})
export const multiply = tool({
description: "Multiply two numbers",
args: {
a: tool.schema.number().describe("First number"),
b: tool.schema.number().describe("Second number"),
},
async execute(args) {
return (args.a * args.b).toString()
},
})
```
This creates two tools: `math_add` and `math_multiply`.
---
#### Name collisions with built-in tools
Custom tools are keyed by tool name. If a custom tool uses the same name as a built-in tool, the custom tool takes precedence.
For example, this file replaces the built-in `bash` tool:
```ts title=".opencode/tools/bash.ts"
import { tool } from "@opencode-ai/plugin"
export default tool({
description: "Restricted bash wrapper",
args: {
command: tool.schema.string(),
},
async execute(args) {
return `blocked: ${args.command}`
},
})
```
:::note
Prefer unique names unless you intentionally want to replace a built-in tool. If you want to disable a built in tool but not override it, use [permissions](/docs/permissions).
:::
---
### Arguments
You can use `tool.schema`, which is just [Zod](https://zod.dev), to define argument types.
```ts "tool.schema"
args: {
query: tool.schema.string().describe("SQL query to execute")
}
```
You can also import [Zod](https://zod.dev) directly and return a plain object:
```ts {6}
import { z } from "zod"
export default {
description: "Tool description",
args: {
param: z.string().describe("Parameter description"),
},
async execute(args, context) {
// Tool implementation
return "result"
},
}
```
---
### Context
Tools receive context about the current session:
```ts title=".opencode/tools/project.ts" {8}
import { tool } from "@opencode-ai/plugin"
export default tool({
description: "Get project information",
args: {},
async execute(args, context) {
// Access context information
const { agent, sessionID, messageID, directory, worktree } = context
return `Agent: ${agent}, Session: ${sessionID}, Message: ${messageID}, Directory: ${directory}, Worktree: ${worktree}`
},
})
```
Use `context.directory` for the session working directory.
Use `context.worktree` for the git worktree root.
---
## Examples
### Write a tool in Python
You can write your tools in any language you want. Here's an example that adds two numbers using Python.
First, create the tool as a Python script:
```python title=".opencode/tools/add.py"
import sys
a = int(sys.argv[1])
b = int(sys.argv[2])
print(a + b)
```
Then create the tool definition that invokes it:
```ts title=".opencode/tools/python-add.ts" {10}
import { tool } from "@opencode-ai/plugin"
import path from "path"
export default tool({
description: "Add two numbers using Python",
args: {
a: tool.schema.number().describe("First number"),
b: tool.schema.number().describe("Second number"),
},
async execute(args, context) {
const script = path.join(context.worktree, ".opencode/tools/add.py")
const result = await Bun.$`python3 ${script} ${args.a} ${args.b}`.text()
return result.trim()
},
})
```
Here we are using the [`Bun.$`](https://bun.com/docs/runtime/shell) utility to run the Python script.
|