MCPO: OpenAPI Proxy for MCP Servers

0.0.20 · active · verified Thu Apr 16

MCPO (Model Context Protocol to OpenAPI Proxy) is a dead-simple proxy that takes an MCP server command and makes it accessible via standard RESTful OpenAPI. It enables tools to "just work" with LLM agents and applications expecting OpenAPI servers, addressing the integration challenges of stdio-based MCP tools within the broader web ecosystem. Developed by the Open WebUI community, MCPO is an active project, with version 0.0.20 released on February 27, 2026.

Common errors

```
What am I missing to get the MCP Server as Http-streamable with the MCPO Proxy? Neither of these commands work: uvx mcpo --port 8002 --api-key "top-secret" --server-type "streamable-http" -- http://127.0.0.1:8000/mcp or uvx mcpo --port 8002 --api-key "top-secret" -- uv run server.py
```
cause `mcpo` treats `streamable-http` servers as remote endpoints that must be pre-running, not as child processes to launch. The `uv run server.py` command is being passed *as the target URL* when it should be running separately.

fix First, start your `streamable-http` MCP server (e.g., `uv run server.py` which exposes it on `http://127.0.0.1:8000/mcp` if configured this way). Then, in a separate terminal, run `uvx mcpo --port 8002 --api-key "top-secret" --server-type "streamable-http" -- http://127.0.0.1:8000/mcp`.
```
mcpo: command not found
```
cause The `mcpo` executable is not in your system's PATH, or the library was not installed in your active Python environment.

fix Ensure you have installed `mcpo` using `pip install mcpo` (or `uv pip install mcpo`). If using a virtual environment, activate it before running the command. If installed globally, ensure your user's PATH includes the directory where pip installs executables.

Warnings

gotcha When running `mcpo` to proxy an MCP server command, arguments specific to the proxied server must be separated from `mcpo`'s arguments using `--` (double dash).
Fix: Always use `--` before the command and arguments of the MCP server you intend to proxy, e.g., `mcpo [mcpo_args] -- [mcp_server_command] [mcp_server_args]`.
gotcha When `mcpo` is configured with `--server-type streamable-http`, it expects the target MCP server to already be running at the provided URL, rather than launching it directly as it would with `stdio` type servers.
Fix: Ensure your `streamable-http` MCP server is independently started and listening on the specified URL *before* you execute the `mcpo` command. For example, run `uv run your_mcp_server.py` in one terminal, then `mcpo --server-type streamable-http -- http://127.0.0.1:8000/mcp` in another.
gotcha While `mcpo` can provide API key authentication, it's crucial to ensure that the API key provided to `mcpo` (`--api-key`) is correctly expected and validated by any downstream clients or AI agents. For more robust authentication, `mcpo` also supports OAuth configuration.
Fix: For simple setups, use `--api-key "YOUR_SECRET"`. For enterprise or production environments, explore `mcpo`'s OAuth configuration options, including `server_url` for dynamic client registration and secure token management.

Install

pip install mcpo With pip
uv pip install mcpo With uv (recommended)

Quickstart

This quickstart demonstrates how to install `mcpo` and then run it to proxy a simple `mcp-server-time` tool. The first command installs `mcpo` and a sample MCP server. The second command starts `mcpo` on port 8000, securing it with an API key, and instructs it to proxy the `mcp-server-time` command. Your proxied API will then be available at `http://localhost:8000` with auto-generated documentation at `http://localhost:8000/docs`.

pip install mcpo uvx mcp-server-time
uvx mcpo --port 8000 --api-key "YOUR_API_KEY" -- uvx mcp-server-time --local-timezone=America/New_York

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