68c800d2a3
### Summary: This enables users to **use** MCP inside the SDK. 1. You add a list of MCP servers to `Agent`, via `mcp_server=[...]` 2. When an agent runs, we look up its MCP tools and add them to the list of tools. 3. When a tool call occurs, we call the relevant MCP server. Notes: 1. There's some refactoring to make sure we send the full list of tools to the Runner/Model etc. 2. Right now, you could have a locally defined tool that conflicts with an MCP defined tool. I didn't add errors for that, will do in a followup. ### Test Plan: See unit tests. Also has an end to end example next PR.
57 lines
1.9 KiB
Python
57 lines
1.9 KiB
Python
from unittest.mock import AsyncMock, patch
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import pytest
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from mcp.types import ListToolsResult, Tool as MCPTool
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from agents.mcp import MCPServerStdio
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from .helpers import DummyStreamsContextManager, tee
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@pytest.mark.asyncio
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@patch("mcp.client.stdio.stdio_client", return_value=DummyStreamsContextManager())
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@patch("mcp.client.session.ClientSession.initialize", new_callable=AsyncMock, return_value=None)
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@patch("mcp.client.session.ClientSession.list_tools")
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async def test_server_caching_works(
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mock_list_tools: AsyncMock, mock_initialize: AsyncMock, mock_stdio_client
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):
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"""Test that if we turn caching on, the list of tools is cached and not fetched from the server
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on each call to `list_tools()`.
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"""
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server = MCPServerStdio(
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params={
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"command": tee,
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},
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cache_tools_list=True,
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)
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tools = [
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MCPTool(name="tool1", inputSchema={}),
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MCPTool(name="tool2", inputSchema={}),
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]
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mock_list_tools.return_value = ListToolsResult(tools=tools)
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async with server:
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# Call list_tools() multiple times
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tools = await server.list_tools()
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assert tools == tools
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assert mock_list_tools.call_count == 1, "list_tools() should have been called once"
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# Call list_tools() again, should return the cached value
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tools = await server.list_tools()
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assert tools == tools
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assert mock_list_tools.call_count == 1, "list_tools() should not have been called again"
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# Invalidate the cache and call list_tools() again
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server.invalidate_tools_cache()
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tools = await server.list_tools()
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assert tools == tools
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assert mock_list_tools.call_count == 2, "list_tools() should be called again"
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# Without invalidating the cache, calling list_tools() again should return the cached value
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tools = await server.list_tools()
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assert tools == tools
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