Map MCP Adapters

A simple demonstration of exposing geocoding and routing tools via an MCP server, and consuming them with a custom LangChain agent.

Project Structure

├── map_server.py      # MCP server exposing geocode and get_directions tools
├── map_client.py      # LangChain client loading MCP tools and running an agent
└── README.md          # This file

Prerequisites

• Python 3.8+

• An OpenAI API key set in OPENAI_API_KEY

• Dependencies:

  • mcp (Model Context Protocol SDK)
  • langchain-mcp-adapters
  • langchain (with OpenAI support)
  • langgraph (prebuilt agents)
  • geopy (for geocoding)

Install with:

pip install mcp langchain-mcp-adapters langchain[openai] langgraph geopy

1. Running the MCP Server

The server exposes two tools:

• geocode(address: str) -> {latitude, longitude}
• get_directions(start: str, end: str) -> List[str]

Start the server on stdio transport:

python map_server.py

Tip: To use HTTP streaming, change mcp.run(transport="stdio") to mcp.run(transport="streamable-http", port=3000).

2. Running the LangChain Client

The client spins up the MCP server, loads its tools, and wires them into a React agent.

python map_client.py

Update the path to map_server.py in map_client.py as needed. The client will print a natural‑language answer, e.g.:

→ Agent’s answer:
 1. Head north from the Eiffel Tower
 2. ...

3. Customization

• Multiple Servers: Use MultiServerMCPClient to combine tools from several MCP servers (e.g., weather, maps).
• HTTP Transport: Switch to streamable-http and use streamablehttp_client for non‑blocking requests.
• Agent Types: Swap AgentType.ZERO_SHOT_REACT_DESCRIPTION for other built‑in or custom agent templates.

🧪 Sample Output

> Entering new AgentExecutor chain...

Invoking: `get_directions` with `{'start': 'Eiffel Tower', 'end': 'Louvre'}`

Processing request of type CallToolRequest
['1. Head north from Eiffel Tower', '2. Turn right onto Main St', '3. Continue until you reach Louvre', '4. You have arrived.']
Here are the directions from the Eiffel Tower to the Louvre:

1. Head north from the Eiffel Tower.
2. Turn right onto Main St.
3. Continue until you reach the Louvre.
4. You have arrived.

## License

MIT © 2025