mcpforge

Ship an MCP server in 5 lines of Python.

Before                              After
──────                              ─────
~200 lines of                       @serve
JSON-RPC stdio                      class MarketTools:
boilerplate, schema                     @tool
generation, error                       def latest_price(self, symbol: str) -> float: ...
handling, lifecycle                     @tool
management.                             def search(self, query: str) -> list[dict]: ...

                                    $ python -m mcpforge run market:MarketTools
                                    ✓ MCP server running on stdio

Why mcpforge

The Model Context Protocol (MCP) is the open standard Claude, Cursor, and an exploding ecosystem of AI tools use to call external functions. It's powerful — and writing a server is currently miserable.

You write the same JSON-RPC framing, schema generation, dispatch loop, and error handling on every project. mcpforge erases all of it. Annotate your class. Type-hint your methods. You're done.

from mcpforge import serve, tool

@serve(name="market_tools", version="0.1.0")
class MarketTools:
    """Market data tools for AI agents."""

    @tool(description="Get the latest price for a symbol")
    def latest_price(self, symbol: str) -> float:
        return fetch_price(symbol)

    @tool
    def search(self, query: str, limit: int = 10) -> list[dict]:
        """Search ticker symbols matching `query`."""
        return run_search(query, limit)

That's a complete, spec-compliant MCP server. Type hints become JSON Schema. Docstrings become tool descriptions. Returns are auto-serialized.

60-second quickstart

pip install mcpforge

# hello.py
from mcpforge import serve, tool

@serve(name="hello", version="0.1.0")
class HelloTools:
    @tool
    def greet(self, name: str = "world") -> str:
        """Say hello to someone."""
        return f"Hello, {name}!"

python -m mcpforge run hello:HelloTools

You now have a working MCP server speaking JSON-RPC 2.0 over stdio.

How it works

1. @serve tags a class as an MCP server (name, version, capabilities).
2. @tool registers methods as MCP tools.
3. @resource(uri=...) registers methods as MCP resources.
4. mcpforge introspects each method's signature and produces a JSON Schema — primitives, list[T], dict[str, T], Literal[...], Optional[T], dataclasses, and Pydantic models all just work.
5. python -m mcpforge run mod:Class boots the stdio loop, handles initialize / tools/list / tools/call / resources/list / resources/read, and reports JSON-RPC errors with proper codes.

No external MCP SDK. Just stdlib json + pydantic for schema niceties.

Built-in servers

Two batteries-included servers you can drop in today:

# Filesystem tools (sandboxed to a root directory)
python -m mcpforge run mcpforge.builtin.filesystem:FilesystemTools

# HTTP fetch tools
python -m mcpforge run mcpforge.builtin.http:HttpTools

FilesystemTools exposes list_dir, read_file, search — sandboxed with path traversal checks. HttpTools exposes fetch_url with size limits.

Plug into Claude Desktop

Add to ~/Library/Application Support/Claude/claude_desktop_config.json:

{
  "mcpServers": {
    "market": {
      "command": "python",
      "args": ["-m", "mcpforge", "run", "market:MarketTools"],
      "cwd": "/path/to/your/project"
    }
  }
}

Restart Claude Desktop. Your tools appear in the conversation.

Plug into Cursor

~/.cursor/mcp.json:

{
  "mcpServers": {
    "market": {
      "command": "python",
      "args": ["-m", "mcpforge", "run", "market:MarketTools"]
    }
  }
}

Comparison

Inspect the wire format

python -m mcpforge inspect market:MarketTools

Prints the exact tools/list payload your clients will see.

Roadmap

• Tools (call, list)
• Resources (read, list)
• Type-hint -> JSON Schema (Pydantic v2, dataclasses, Literal, Optional)
• Built-in filesystem and http servers
• Resource subscriptions
• Prompts capability
• Sampling capability
• WebSocket / HTTP-SSE transport (optional [http] extra)
• Async tools (async def)
• OTel tracing hooks

License

MIT — see LICENSE.

Author: thechifura. Sibling to quantflow and strategos.