MCP Server Builder

Model Context Protocol (MCP) server for searching MCP protocol and FastMCP documentation.

This MCP server helps you build correct MCP servers by providing searchable access to the official MCP specification and FastMCP framework documentation, always reflecting the current state of the protocol.

Features

• BM25 Search — Advanced full-text search with Porter stemming and n-gram indexing
• Stop Word Removal — 179 common English stop words filtered for better relevance
• Domain Term Preservation — MCP-specific terms (mcp, json, rpc, stdio) kept intact
• Lazy Loading — Fast startup with on-demand content fetching
• Always Current — Indexes live documentation from llms.txt sources on startup

Data Sources

The server indexes documentation from these curated llms.txt sources:

| Source | Description | |--------|-------------| | modelcontextprotocol.io/llms.txt | Official MCP protocol specification | | gofastmcp.com/llms.txt | FastMCP Python framework documentation |

Prerequisites

1. Install uv from Astral
2. Install Python 3.13 or newer using uv python install 3.13

Installation

Configure in your MCP client:

{
  "mcpServers": {
    "mcp-server-builder": {
      "command": "uvx",
      "args": ["mcp-server-builder@latest"],
      "disabled": false,
      "autoApprove": []
    }
  }
}

Config file locations:

• Claude Desktop (macOS): ~/Library/Application Support/Claude/claude_desktop_config.json
• Claude Desktop (Windows): %APPDATA%\Claude\claude_desktop_config.json
• Windsurf: ~/.codeium/windsurf/mcp_config.json
• Kiro: .kiro/settings/mcp.json in your project

Install from PyPI

# Using uv
uv add mcp-server-builder

# Using pip
pip install mcp-server-builder

Basic Usage

Example prompts to try:

• "How do I define tools in FastMCP?"
• "What is the MCP lifecycle?"
• "Show me stdio transport configuration"
• "How to handle tool errors in MCP?"
• "What are MCP resources and how do I use them?"

Available Tools

search_mcp_docs

Search MCP protocol AND FastMCP framework documentation with ranked results and snippets.

search_mcp_docs(query: str, k: int = 5, source: str | None = None) -> list[dict]

| Parameter | Type | Default | Description | |-----------|------|---------|-------------| | query | str | required | Search query (e.g., "tool input schema", "stdio transport") | | k | int | 5 | Maximum number of results to return | | source | str | None | None | Optional filter: "mcp" for protocol docs, "fastmcp" for framework docs |

Returns: List of results with url, title, score, snippet, and source.

Examples:

# Search both sources
search_mcp_docs("how to define tools", k=3)

# Search only MCP protocol docs
search_mcp_docs("lifecycle", source="mcp")

# Search only FastMCP framework docs
search_mcp_docs("authentication", source="fastmcp")

fetch_mcp_doc

Retrieve full documentation page content by URL from MCP protocol or FastMCP framework docs.

fetch_mcp_doc(uri: str) -> dict

| Parameter | Type | Default | Description | |-----------|------|---------|-------------| | uri | str | required | Document URL (http/https from supported domains) |

Supported domains: modelcontextprotocol.io, gofastmcp.com

Returns: Dictionary with url, title, content, source (or error on failure).

Example:

# Fetch MCP protocol doc
fetch_mcp_doc("https://modelcontextprotocol.io/docs/concepts/tools")

# Fetch FastMCP framework doc
fetch_mcp_doc("https://gofastmcp.com/tutorials/tools")

Workflow Example

Step 1: Search for relevant documentation

search_mcp_docs("FastMCP tool decorator", k=5)

Step 2: Fetch full content of the most relevant result

fetch_mcp_doc("https://gofastmcp.com/tutorials/tools")

Architecture

llms.txt URLs (MCP + FastMCP)
    ↓ startup
BM25 index with stemmed tokens + n-grams (titles only, fast)
    ↓ search request
Stem query → match unigrams/bigrams/trigrams → BM25 rank
    ↓ top-k
Lazy content hydration → snippet extraction
    ↓ response
{ url, title, score, snippet }

Development

# Clone and install
git clone https://github.com/praveenc/mcp-server-builder.git
cd mcp-server-builder
uv sync --dev
source .venv/bin/activate

# Run tests
uv run pytest

# Run with MCP Inspector
npx @anthropic-ai/mcp-inspector uv run mcp-server-builder

# Linting and type checking
uv run ruff check src tests
uv run pyright

License

MIT - see LICENSE for details.

Contributing

Contributions welcome! Please open an issue or submit a pull request.

Support

For issues and questions, use the GitHub issue tracker