Pydantic Documentation MCP Server

A Model Context Protocol (MCP) server providing local-first access to Pydantic and Pydantic AI documentation with BM25-powered full-text search.

Features

• Local-first architecture - Offline-only mode by default

• BM25 full-text search - Fast semantic search across all docs

• Git-based extraction - Direct from source repositories (no HTML scraping)

• Pre-processed data - JSONL files included for instant setup

• Auto-initialization - Builds indices automatically on first run

• Complete coverage - Pydantic v2 and Pydantic AI documentation

Related MCP server: MPC Docs Server

Requirements

• Python 3.12+

• uv package manager

• ~15MB disk space (with indices)

Quick Start

# Clone and install
git clone <repository-url>
cd mcp_pydantic_docs
uv sync

# Server auto-builds indices on first run
uv run mcp-pydantic-docs

MCP Client Configuration

Add to your MCP settings (e.g., cline_mcp_settings.json):

{
  "mcpServers": {
    "pydantic-docs": {
      "command": "uv",
      "args": [
        "--directory",
        "/absolute/path/to/mcp_pydantic_docs",
        "run",
        "mcp-pydantic-docs"
      ]
    }
  }
}

Architecture

How It Works

1. Source Extraction (source_extractor.py) - Clones Pydantic repos, extracts documentation from markdown/docstrings → JSONL

2. Index Building (indexer.py) - Processes JSONL files → BM25 search indices

3. MCP Server (mcp.py) - Serves documentation via MCP tools

4. Shared Utilities (utils.py) - HTML/text processing, normalization

Directory Structure

mcp_pydantic_docs/
├── mcp_pydantic_docs/          # Source code
│   ├── mcp.py                  # MCP server
│   ├── source_extractor.py     # Git-based doc extraction
│   ├── indexer.py              # BM25 index builder
│   ├── utils.py                # Shared utilities
│   └── setup.py                # Setup CLI
├── data/                       # Search data
│   ├── pydantic.jsonl          # Pydantic docs (2.9MB, in git)
│   ├── pydantic_ai.jsonl       # Pydantic AI docs (3.3MB, in git)
│   ├── *_bm25.pkl              # BM25 index (generated)
│   └── *_records.pkl           # Document records (generated)
└── docs_raw/                   # Source repos (not in git)
    ├── pydantic/               # Cloned from GitHub
    └── pydantic_ai/            # Cloned from GitHub

Data Flow

GitHub Repos → source_extractor.py → JSONL files → indexer.py → BM25 indices → mcp.py → MCP Client

Available Tools

Search & Retrieval

• pydantic_search(query, k=10) - Full-text search with BM25 ranking

• pydantic_get(path_or_url, max_chars=None) - Fetch full documentation page

• pydantic_section(path_or_url, anchor) - Extract specific section

• pydantic_api(symbol, anchor=None) - Jump to API documentation

Health & Admin

• health_ping() - Server health check

• health_validate() - Validate search indices

• pydantic_mode() - Server configuration

• admin_cache_status() - Detailed cache status

• admin_rebuild_indices() - Rebuild search indices

Updating Documentation

Rebuild from Existing JSONL

uv run python -m mcp_pydantic_docs.indexer

Extract Fresh Documentation

# Check status
uv run python -m mcp_pydantic_docs.setup --status

# Download and extract from GitHub
uv run python -m mcp_pydantic_docs.setup --download --build-index

# Clean cache
uv run python -m mcp_pydantic_docs.setup --clean

Configuration

Environment Variables

• PDA_DOC_ROOT - Pydantic v2 source path

• PDA_DOC_ROOT_AI - Pydantic AI source path

• PDA_DATA_DIR - Data directory path

Offline Mode

Default: Enabled (OFFLINE_ONLY = True in mcp.py)

• Blocks remote requests

• Validates file paths

• All content from local cache

Development

Run Tests

uv run pytest

Code Quality

uv run black mcp_pydantic_docs/  # Format
uv run ruff check .              # Lint
uv run mypy mcp_pydantic_docs/   # Type check

Troubleshooting

Search indices not found:

uv run python -m mcp_pydantic_docs.indexer

Wrong Python version:

uv python install 3.12

Server won't start:

# Test standalone
uv run mcp-pydantic-docs

# Check indices
uv run python -m mcp_pydantic_docs.setup --status

License

MIT License - see LICENSE file.

Contributing

See CONTRIBUTING.md for:

• Development setup

• Code style

• Testing requirements

• Pull request process