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Joan Xie d90365e626

feat: add UV runtime support in manifest v0.4

Add UV as a new server type for Python extensions that use UV runtime
for dependency management instead of bundling dependencies.

Schema changes (v0.4):
- Add "uv" to server.type enum
- Make mcp_config optional (not needed for UV type)
- UV extensions rely on pyproject.toml for dependencies

Documentation:
- Add UV runtime section to MANIFEST.md explaining benefits and usage
- Update README.md to recommend UV runtime for Python
- Add complete hello-world-uv example

Benefits of UV runtime:
- Cross-platform support (Windows/macOS/Linux, Intel/ARM)
- Small bundle size (~100 KB vs 5-10 MB)
- Handles compiled dependencies portably
- No user Python installation required

Example manifest:
{
  "manifest_version": "0.4",
  "server": {
    "type": "uv",
    "entry_point": "src/server.py"
  }
}

Co-authored-by: Joan <joan@anthropic.com>

2025-12-02 21:22:19 -08:00

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Hello World UV Runtime Example (Experimental)

Note: UV runtime support is experimental and may change in future versions.

This example demonstrates a minimal MCP server using UV runtime.

What is UV Runtime?

UV runtime lets Claude Desktop automatically manage Python and dependencies for your extension:

Downloads the correct Python version for the user's platform
Creates an isolated virtual environment
Installs dependencies from pyproject.toml
Works cross-platform (Windows, macOS, Linux) without user setup

Structure

hello-world-uv/
├── manifest.json       # server.type = "uv"
├── pyproject.toml      # Dependencies listed here
├── .mcpbignore        # Exclude build artifacts
└── src/
    └── server.py       # MCP server implementation

Key Differences from Python Runtime

UV Runtime (this example):

server.type = "uv"
No bundled dependencies
No mcp_config needed
Small bundle size (~2 KB)
Works on any platform

Python Runtime (traditional):

server.type = "python"
Must bundle dependencies in server/lib/
Requires mcp_config with PYTHONPATH
Larger bundle size
Only works with pure Python (no compiled deps)

Installing

mcpb pack

Install the generated .mcpb file in Claude Desktop.

Testing Locally

# Install dependencies
uv sync

# Run server
uv run src/server.py

Tools

say_hello - Greets a person by name

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