emcee is a tool that provides a Model Context Protocol (MCP) server for any web application with an OpenAPI specification. You can use emcee to connect Claude Desktop and other apps to external tools and data services, similar to ChatGPT plugins.
If you're on macOS and have Homebrew installed, you can get up-and-running quickly.
# Install emcee
brew install loopwork-ai/tap/emceeMake sure you have Claude Desktop installed.
To configure Claude Desktop for use with emcee:
- Open Claude Desktop Settings (⌘,)
- Select the "Developer" section in the sidebar
- Click "Edit Config" to open the configuration file
The configuration file should be located in the Application Support directory. You can also open it directly in VSCode using:
code ~/Library/Application\ Support/Claude/claude_desktop_config.jsonAdd the following configuration to add the weather.gov MCP server:
{
"mcpServers": {
"weather": {
"command": "emcee",
"args": [
"https://api.weather.gov/openapi.json"
]
}
}
}After saving the file, quit and re-open Claude. You should now see 🔨57 in the bottom right corner of your chat box. Click on that to see a list of all the tools made available to Claude through MCP.
Start a new chat and ask it about the weather where you are.
What's the weather in Portland, OR?
Claude will consult the tools made available to it through MCP and request to use one if deemed to be suitable for answering your question. You can review this request and either approve or deny it.
If you allow, Claude will communicate with the MCP and use the result to inform its response.
Tip
Building agents? Want to deploy remote MCP servers? Reach out to us at [email protected]
MCP provides a standardized way to connect AI models to tools and data sources. It's still early days, but there are already a variety of available servers for connecting to browsers, developer tools, and other systems.
We think emcee is a convenient way to connect to services that don't have an existing MCP server implementation — especially for services you're building yourself. Got a web app with an OpenAPI spec? You might be surprised how far you can get without a dashboard or client library.
Use the installer script to download and install a pre-built release of emcee for your platform (Linux x86-64/i386/arm64 and macOS Intel/Apple Silicon).
# fish
sh (curl -fsSL https://get.emcee.sh | psub)
# bash, zsh
sh <(curl -fsSL https://get.emcee.sh)Install emcee using Homebrew from Loopwork's tap.
brew install loopwork-ai/tap/emceePrebuilt Docker images with emcee are available.
docker run -it ghcr.io/loopwork-ai/emceeRequires go 1.23 or later.
git clone https://github.com/loopwork-ai/emcee.git
cd emcee
go build -o emcee cmd/emcee/main.goOnce built, you can run in place (./emcee)
or move it somewhere in your PATH, like /usr/local/bin.
Usage:
emcee [spec-path-or-url] [flags]
Flags:
--basic-auth string Basic auth value (either user:pass or base64 encoded, will be prefixed with 'Basic ')
--bearer-auth string Bearer token value (will be prefixed with 'Bearer ')
-h, --help help for emcee
--raw-auth string Raw value for Authorization header
--retries int Maximum number of retries for failed requests (default 3)
-r, --rps int Maximum requests per second (0 for no limit)
-s, --silent Disable all logging
--timeout duration HTTP request timeout (default 1m0s)
-v, --verbose Enable debug level logging to stderr
--version version for emceeemcee implements Standard Input/Output (stdio) transport for MCP, which uses JSON-RPC 2.0 as its wire format.
When you run emcee from the command-line, it starts a program that listens on stdin, outputs to stdout, and logs to stderr.
For APIs that require authentication, emcee supports several authentication methods:
| Authentication Type | Example Usage | Resulting Header |
|---|---|---|
| Bearer Token | --bearer-auth="abc123" |
Authorization: Bearer abc123 |
| Basic Auth | --basic-auth="user:pass" |
Authorization: Basic dXNlcjpwYXNz |
| Raw Value | --raw-auth="Custom xyz789" |
Authorization: Custom xyz789 |
These authentication values can be provided directly or as 1Password secret references.
When using 1Password references:
- Use the format
op://vault/item/field(e.g.--bearer-auth="op://Shared/X/credential") - Ensure the 1Password CLI (op) is installed and available in your
PATH - Sign in to 1Password before running emcee or launching Claude Desktop
# Install op
brew install 1password-cli
# Sign in 1Password CLI
op signin{
"mcpServers": {
"twitter": {
"command": "emcee",
"args": [
"--bearer-auth=op://shared/x/credential",
"https://api.twitter.com/2/openapi.json"
]
}
}
}
Important
emcee doesn't use auth credentials when downloading OpenAPI specifications from URLs provided as command arguments. If your OpenAPI specification requires authentication to access, first download it to a local file using your preferred HTTP client, then provide the local file path to emcee.
You can transform OpenAPI specifications before passing them to emcee using standard Unix utilities. This is useful for:
- Selecting specific endpoints to expose as tools with jq or yq
- Modifying descriptions or parameters with OpenAPI Overlays
- Combining multiple specifications with Redocly
For example,
you can use jq to include only the point tool from weather.gov.
cat path/to/openapi.json | \
jq 'if .paths then .paths |= with_entries(select(.key == "/points/{point}")) else . end' | \
emceeYou can interact directly with the provided MCP server by sending JSON-RPC requests.
Note
emcee provides only MCP tool capabilities. Other features like resources, prompts, and sampling aren't yet supported.
Request
{"jsonrpc": "2.0", "method": "tools/list", "params": {}, "id": 1}Response
{
"jsonrpc":"2.0",
"result": {
"tools": [
// ...
{
"name": "tafs",
"description": "Returns Terminal Aerodrome Forecasts for the specified airport station.",
"inputSchema": {
"type": "object",
"properties": {
"stationId": {
"description": "Observation station ID",
"type": "string"
}
},
"required": ["stationId"]
}
},
// ...
]
},
"id": 1
}Request
{"jsonrpc": "2.0", "method": "tools/call", "params": { "name": "taf", "arguments": { "stationId": "KPDX" }}, "id": 1}Response
{
"jsonrpc":"2.0",
"content": [
{
"type": "text",
"text": /* Weather forecast in GeoJSON format */,
"annotations": {
"audience": ["assistant"]
}
}
]
"id": 1
}The MCP Inspector is a tool for testing and debugging MCP servers. If Claude and/or emcee aren't working as expected, the inspector can help you understand what's happening.
npx @modelcontextprotocol/inspector emcee https://api.weather.gov/openapi.json
# 🔍 MCP Inspector is up and running at http://localhost:5173 🚀open http://localhost:5173emcee is licensed under the Apache License, Version 2.0.