139 lines
4.2 KiB
Markdown
139 lines
4.2 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 a client UI (default port 5173) and an MCP proxy server (default port 3000). Open the client UI in your browser to use the inspector. 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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### Using a Configuration File
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The inspector supports configuration files to store settings for different MCP servers. This is useful when working with multiple servers or complex configurations:
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```bash
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npx @modelcontextprotocol/inspector --config path/to/config.json --server everything
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```
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Example configuration file:
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```json
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{
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"mcpServers": {
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"everything": {
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"command": "npx",
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"args": ["@modelcontextprotocol/server-everything"],
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"env": {
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"hello": "Hello MCP!"
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}
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},
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"my-server": {
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"command": "node",
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"args": ["build/index.js", "arg1", "arg2"],
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"env": {
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"key": "value",
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"key2": "value2"
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}
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}
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}
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}
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```
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### CLI Mode
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CLI mode enables programmatic interaction with MCP servers from the command line, ideal for scripting, automation, and integration with coding assistants. This creates an efficient feedback loop for MCP server development.
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```bash
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npx @modelcontextprotocol/inspector --cli node build/index.js
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```
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The CLI mode supports most operations across tools, resources, and prompts. A few examples:
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```bash
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# Basic usage
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npx @modelcontextprotocol/inspector --cli node build/index.js
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# With config file
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npx @modelcontextprotocol/inspector --cli --config path/to/config.json --server myserver
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# List available tools
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npx @modelcontextprotocol/inspector --cli node build/index.js --method tools/list
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# Call a specific tool
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npx @modelcontextprotocol/inspector --cli node build/index.js --method tools/call --tool-name mytool --tool-args key=value --tool-args another=value2
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# List available resources
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npx @modelcontextprotocol/inspector --cli node build/index.js --method resources/list
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# List available prompts
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npx @modelcontextprotocol/inspector --cli node build/index.js --method prompts/list
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# Connect to a remote MCP server
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npx @modelcontextprotocol/inspector --cli https://my-mcp-server.example.com
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# Call a tool on a remote server
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npx @modelcontextprotocol/inspector --cli https://my-mcp-server.example.com --method tools/call --tool-name remotetool --tool-args param=value
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# List resources from a remote server
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npx @modelcontextprotocol/inspector --cli https://my-mcp-server.example.com --method resources/list
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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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### 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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