emcee is a tool that provides a Model Context Protocol (MCP) server for any web application that has an OpenAPI specification. With emcee, you can connect Claude Desktop and other applications to external tools and data services, similar to ChatGPT plugins.
Purpose emcee's core purpose is to automatically generate an MCP server for an existing OpenAPI specification, enabling AI models to call the interfaces provided by a web application through a standardized protocol. For services that do not yet have a ready-made MCP server implementation, especially services that users are developing themselves, emcee provides a convenient way to integrate. If a web application already has an OpenAPI specification, you can try integrating it without an additional dashboard or client library.
Main capabilities
- Generate an MCP server from an OpenAPI specification for use by applications that support MCP, such as Claude Desktop.
- Implement MCP's Standard Input/Output (stdio) transport, using JSON-RPC 2.0 as the wire format. When running emcee from the command line, the program listens on stdin, outputs to stdout, and writes logs to stderr.
- Support APIs that require authentication, providing multiple authentication methods, with authentication values that can be provided directly or by using 1Password secret references (in the format op://vault/item/field). When using 1Password references, you need to install the 1Password CLI and ensure it is in PATH, and log in to 1Password before running emcee or starting Claude Desktop.
- Support the HTTP QUERY method defined by RFC 10008: OpenAPI 3.2 specifications can use the native query Path Item operation; older OpenAPI 3.x specifications can use the x-query compatibility extension, whose value is parsed according to the standard OpenAPI Operation Object, registered as an MCP tool, and marked as read-only and idempotent.
- Provide a prebuilt release installation script (supporting Linux x86-64/i386/arm64 and macOS Intel/Apple Silicon), Homebrew installation, andprebuilt Docker images.
- Can be built from source, requiring Go 1.24 or later. After building, it can be run in place (./emcee) or moved to a location in PATH, such as /usr/local/bin.
- Can be used with Unix tools such as jq, yq, OpenAPI Overlays, and Redocly to transform the OpenAPI specification before passing it to emcee, for example selecting only specific endpoints (such as using jq to include only the weather.gov point tool), modifying descriptions or parameters, or merging multiple specifications.
- Support interacting with the provided MCP server by sending JSON-RPC requests directly.
Usage Taking Claude Desktop as an example, the configuration steps include: open Claude Desktop settings (⌘ ,), select the "Developer" section in the sidebar, click "Edit Config" to open the configuration file (located in the Application Support directory, and it can also be opened directly with VSCode). Add the corresponding configuration to connect to the weather.gov MCP server. After saving the file, quit and reopen Claude; a 🔨57 marker will appear in the lower right corner of the chat box, and clicking it will show all tools provided to Claude through MCP. Start a new conversation and ask about the weather; Claude will query the available tools, and if it considers them suitable, it will request to use them, and the user can approve or deny. If allowed, Claude will communicate with MCP and use the results to generate a response.
Note that emcee does not use authentication credentials when downloading the OpenAPI specification from a URL provided as a command-line argument. If the OpenAPI specification itself requires authentication to access, you should first download it to a local file using an HTTP client, and then provide the local file path to emcee.
Applicable scenarios
- Connect applications that support MCP, such as Claude Desktop, to external tools and data services.
- Quickly generate an MCP integration layer for web applications that already have an OpenAPI specification but lack an MCP server implementation.
- When developing your own web service, quickly provide MCP tool capabilities through an OpenAPI specification.
- Use MCP Inspector (a tool for testing and debugging MCP servers) to troubleshoot Claude and/or emcee'sWork is abnormal.
Limitations emcee only provides MCP tool capabilities and does not currently support features such as resources, prompts, and sampling. Using 1Password secret references requires the corresponding prerequisites to be met. Authentication credentials are not used when downloading OpenAPI specifications from a URL.
License This project is released under the MIT License, see the LICENSE file for details.
