fastmcp/examples/sampling/README.md
Rach Granville dd803a0d7f
docs: quote pip extras install examples (#4568)
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Co-authored-by: Jeremiah Lowin <153965+jlowin@users.noreply.github.com>
2026-07-20 11:09:50 -04:00

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# Sampling Examples
These examples demonstrate FastMCP's sampling API, which allows server tools to request LLM completions from the client.
## Prerequisites
```bash
pip install 'fastmcp[anthropic]'
export ANTHROPIC_API_KEY=your-key
```
Or run directly with `uv`:
```bash
uv run examples/sampling/text.py
```
## Examples
### Simple Text Sampling (`text.py`)
Basic sampling flow where a server tool requests an LLM completion:
```bash
uv run examples/sampling/text.py
```
### Structured Output (`structured_output.py`)
Uses `result_type` to get validated Pydantic models from the LLM:
```bash
uv run examples/sampling/structured_output.py
```
### Tool Use (`tool_use.py`)
Gives the LLM tools to use during sampling (calculator, time, dice):
```bash
uv run examples/sampling/tool_use.py
```
### Server Fallback (`server_fallback.py`)
Configures a fallback sampling handler on the server, enabling sampling even when clients don't support it:
```bash
uv run examples/sampling/server_fallback.py
```
## Using OpenAI Instead
To use OpenAI instead of Anthropic, change the handler:
```python
from fastmcp.client.sampling.handlers.openai import OpenAISamplingHandler
handler = OpenAISamplingHandler(default_model="gpt-4o-mini")
```
And install with `pip install 'fastmcp[openai]'`.