85 lines
3.3 KiB
Markdown
85 lines
3.3 KiB
Markdown
# MCP Inspector
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The MCP inspector is a developer tool for testing and debugging MCP servers.
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## Running the Inspector
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### From an MCP server repository
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To inspect an MCP server implementation, there's no need to clone this repo. Instead, use `npx`. For example, if your server is built at `build/index.js`:
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```bash
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npx @modelcontextprotocol/inspector node build/index.js
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```
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You can pass both arguments and environment variables to your MCP server. Arguments are passed directly to your server, while environment variables can be set using the `-e` flag:
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```bash
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# Pass arguments only
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npx @modelcontextprotocol/inspector build/index.js arg1 arg2
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# Pass environment variables only
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npx @modelcontextprotocol/inspector -e KEY=value -e KEY2=$VALUE2 node build/index.js
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# Pass both environment variables and arguments
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npx @modelcontextprotocol/inspector -e KEY=value -e KEY2=$VALUE2 node build/index.js arg1 arg2
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# Use -- to separate inspector flags from server arguments
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npx @modelcontextprotocol/inspector -e KEY=$VALUE -- node build/index.js -e server-flag
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```
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The inspector runs both an MCP Inspector (MCPI) client UI (default port 6274) and an MCP Proxy (MCPP) server (default port 6277). Open the MCPI client UI in your browser to use the inspector. (These ports are derived from the T9 dialpad mapping of MCPI and MCPP respectively, as a mnemonic). You can customize the ports if needed:
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```bash
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CLIENT_PORT=8080 SERVER_PORT=9000 npx @modelcontextprotocol/inspector node build/index.js
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```
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For more details on ways to use the inspector, see the [Inspector section of the MCP docs site](https://modelcontextprotocol.io/docs/tools/inspector). For help with debugging, see the [Debugging guide](https://modelcontextprotocol.io/docs/tools/debugging).
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### Authentication
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The inspector supports bearer token authentication for SSE connections. Enter your token in the UI when connecting to an MCP server, and it will be sent in the Authorization header.
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### Security Considerations
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The MCP Inspector includes a proxy server that can run and communicate with local MCP processes. The proxy server should not be exposed to untrusted networks as it has permissions to spawn local processes and can connect to any specified MCP server.
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### Configuration
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The MCP Inspector supports the following configuration settings. To change them click on the `Configuration` button in the MCP Inspector UI :
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| Name | Purpose | Default Value |
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| -------------------------- | ----------------------------------------------------------------------------------------- | ------------- |
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| MCP_SERVER_REQUEST_TIMEOUT | Maximum time in milliseconds to wait for a response from the MCP server before timing out | 10000 |
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| MCP_PROXY_FULL_ADDRESS | The full URL of the MCP Inspector proxy server (e.g. `http://10.2.1.14:2277`) | `null` |
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### From this repository
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If you're working on the inspector itself:
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Development mode:
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```bash
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npm run dev
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```
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> **Note for Windows users:**
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> On Windows, use the following command instead:
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>
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> ```bash
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> npm run dev:windows
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> ```
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Production mode:
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```bash
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npm run build
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npm start
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```
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## License
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This project is licensed under the MIT License—see the [LICENSE](LICENSE) file for details.
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