Polars Docs MCP

A FastMCP tool to search and retrieve Polars API documentation with support for multiple transport methods.

Features

• Automatically discover Polars public components (classes, functions, submodules).

• Search Polars API by component or query string.

• Get current Polars version and package information.

• Returns structured JSON with API signatures and descriptions.

• Support for multiple transport methods: STDIO, Streamable HTTP, and SSE.

• Integrates with mcp for seamless LLM-powered workflows.

By leveraging Python's built‑in introspection to reflectively discover every public class, function, and submodule in Polars at runtime, I eliminate the cost, fragility, and maintenance burden of web‑scraping or managing an external documentation database. This approach guarantees 100% up‑to‑date accuracy with every library release, requires no complex text cleaning or embedding pipelines, and avoids the heavy infrastructure overhead of semantic search—making it both simpler and far more efficient for real‑time API lookup.

Related MCP server: MCP Server Builder

Usage

1. Claude Desktop Config (Recommended)

{
    "mcpServers": {
        "polarsapifinder": {
            "command": "uv",
            "args": [
                "--directory",
                "/PATH/TO/polars-docs-mcp",
                "run",
                "polarsdocsfinder.py"
            ]
        }
    }
}

2. Manual Execution with Transport Options

STDIO (Default - Best for Claude Desktop)

python polarsdocsfinder.py
# or explicitly:
python polarsdocsfinder.py --transport stdio

Streamable HTTP (Best for Web Deployments)

python polarsdocsfinder.py --transport streamable-http
# With custom settings:
python polarsdocsfinder.py --transport streamable-http --host 0.0.0.0 --port 8080 --path /api/mcp

SSE (For Legacy Client Compatibility)

python polarsdocsfinder.py --transport sse
# With custom settings:
python polarsdocsfinder.py --transport sse --host 0.0.0.0 --port 9000

Command Line Arguments

• --transport: Choose transport method (stdio, streamable-http, sse) - Default: stdio

• --host: Host address for HTTP/SSE transports - Default: 127.0.0.1

• --port: Port number for HTTP/SSE transports - Default: 8111

• --path: URL path for streamable-http transport - Default: /mcp

3. Visual Testing of MCP Server

npx @modelcontextprotocol/inspector uv run polarsdocsfinder.py

Requires Python 3.11+.

Tool Endpoints

• get_polars_version(): Get current Polars version and package information.

• list_polars_components(): List all high-level Polars API components.

• search_polars_docs(api_refs: list[str] | None, query: str | None, max_results: int = 1000): Search and retrieve API signatures.

• verify_polars_api(api_ref: str): Verify if a Polars API reference is valid.

• list_all_modern_data_stacks(): List modern data stacks compatible with Polars.

Transport Methods

STDIO (Default)

• Best for: Claude Desktop, local tools, command-line scripts

• Usage: Direct integration with Claude Desktop configuration

• Communication: Standard input/output streams

Streamable HTTP

• Best for: Web deployments, REST API integration, browser-based clients

• Usage: Run as HTTP service, connect via HTTP requests

• Communication: HTTP POST requests to the specified endpoint

SSE (Server-Sent Events)

• Best for: Compatibility with existing SSE clients, real-time streaming

• Usage: Legacy system integration

• Communication: Server-sent events over HTTP

Examples Snapshots

Testing HTTP Transport

If running with HTTP transport, you can test the server:

# Start server
python polarsdocsfinder.py --transport streamable-http --port 8111

# Test with curl
curl -X POST http://127.0.0.1:8111/mcp \
  -H "Content-Type: application/json" \
  -d '{"method": "tools/list"}'

License

This project is licensed under the MIT License. See the LICENSE file for details.

Contact

Created by ABC. Report issues or request features at https://github.com/HotTechStack/polars-docs-mcp/issues.