Content
# OpenMCP
OpenMCP makes it easy to turn any OpenAPI specification into an MCP server, and to remix many MCP servers into a single
server with just the tools you need. It supports stdio and sse transports, and works with all of the major chat clients.
To get started, run this command:
```bash
npx -y openmcp install <url or file path to openapi specification> --client <chat client>
```
For example, to add the ability to query the weather from Cursor, you could run this:
```bash
# openmcp will prompt you for a security key since this api requires it - but for this weather api the value can be any string
npx -y openmcp install https://api.weather.gov/openapi.json --client cursor
```
And this is what that ends up looking like:
Running the install command will create an `openmcp.json` file for you, and add the openmcp server to your the mcp
config of your target (cursor, claude, etc). Running install again will update any existing `openmcp.json` file, if
present.
### openmcp.json format
The `openmcp.json` file describes the servers that should be started, auth configuration for each, and which tools you
want to expose for each server.
Bellow is a fully annotated example that mixes an openapi based server with a stdio server. Running openmcp with this
config would result in an mcp server with two tools - a tool to get the weather forecast, and a tool to make queries to
a local postgres database.
```jsonc
{
// The configs object is a map of variable names to values. These variables can be referenced in the servers object below.
// If a value is not set, openmcp will attempt to read from an environment variable of the same name.
"configs": {
"weather-gov-api": {
"WEATHER_GOV_API_API_KEY": "foo",
},
"postgres": {
// Or leave blank to read from the environment variable "POSTGRES_URL"
"POSTGRES_URL": "postgresql://localhost/mydb",
},
},
"servers": {
// Example of an openapi server
"weather-gov-api": {
"type": "openapi",
// The openapi specification can be a url or a local file path
"openapi": "https://api.weather.gov/openapi.json",
// The base url of the server
"serverUrl": "https://api.weather.gov",
// Optional headers to send with requests to the server. They can reference values from the configs object above.
"headers": {
"User-Agent": "{{WEATHER_GOV_API_API_KEY}}",
},
// Optional query parameters to send with requests to the server.
"query": {},
// The tools to expose for this server (by operationId). Leaving this empty will expose all tools.
"tools": ["zone_forecast"],
},
// Example of a stdio server
"postgres": {
"command": "npx",
"args": ["-y", "@modelcontextprotocol/server-postgres", "{{POSTGRES_URL}}"],
// The tools allowlist also works with stdio servers. In this case we only expose the relatively safe "query" tool.
"tools": ["query"],
},
},
}
```
### Running the server
The install command will handle this for you, but if you'd like to run an openmcp server manually you can do so with
this command:
```bash
npx -y openmcp run --config <path to openmcp.json config>
```
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