langchain-mcp-tools-py-usage

MCP Tools Usage From LangChain / Example in Python

This simple Model Context Protocol (MCP)
client demonstrates the use of MCP server tools by LangChain ReAct Agent.

It leverages a utility function convert_mcp_to_langchain_tools() from
langchain_mcp_tools.
This function handles parallel initialization of specified multiple MCP servers
and converts their available tools into a list of LangChain-compatible tools
(list[BaseTool]).

Google GenAI's gemini-2.5-flash is used as the LLM.
For convenience, code for OpenAI's and Anthropic's LLMs are also included and commented out.

A bit more realistic (conversational) MCP Client is available
here

A typescript equivalent of this MCP client is available
here

Prerequisites

• Python 3.11+
• [optional] uv (uvx)
  installed to run Python package-based MCP servers
• [optional] npm 7+ (npx)
  to run Node.js package-based MCP servers
• LLM API keys from
  OpenAI,
  Anthropic,
  and/or
  Google GenAI
  as needed

Usage

1. Install dependencies:

   make install
   

2. Setup API key:

   cp .env.template .env
   

   • Update .env as needed.
   • .gitignore is configured to ignore .env
     to prevent accidental commits of the credentials.

3. Run the app:

   make start
   

   It takes a while on the first run.

Simple Exapmle Code for Streamable HTTP Authentiocation

A simple example of showing how to implement an OAuth client provider and
use it with the langchain-mcp-tools library can be found
in src/streamable_http_oauth_test_client.py.

For testing purposes, a sample MCP server with OAuth authentication support
that works with the above client is provided
in src/streamable_http_oauth_test_server.py.

You can run the server with make run-streamable-http-oauth-test-server
and the client with make run-streamable-http-oauth-test-client.