MCP Inspector as MCP Server

A lean MCP server that enables LLMs to inspect and test other MCP servers. This is a self-contained implementation that uses the MCP SDK directly, without shelling out to external CLIs.

Features

Direct SDK integration: Uses @modelcontextprotocol/sdk directly for both server and client operations
All transport types: Supports stdio, SSE, and HTTP (streamable) transports
Minimal footprint: Single dependency (@modelcontextprotocol/sdk), ~300 lines of code
Full MCP inspection: List tools, call tools, list resources, read resources, list prompts, get prompts

Installation

npm install
npm run build

Usage

As an MCP Server

Add to your MCP config. While there are slight variances between different harnesses, the general format is the same:

{
  "mcpServers": {
    "mcp-inspector": {
      "command": "node",
      "args": ["/path/to/mcp-inspector-as-mcp-server/dist/server.js"]
    }
  }
}

Available Tools

Tool	Description
`insp_tools_list`	List all tools exposed by an MCP server
`insp_tools_call`	Call a tool on an MCP server
`insp_resources_list`	List all resources exposed by an MCP server
`insp_resources_read`	Read a specific resource
`insp_resources_templates`	List resource templates
`insp_prompts_list`	List all prompts
`insp_prompts_get`	Get a specific prompt

Connection Parameters

All tools accept the following connection parameters:

For stdio transport (local commands):

command: Command to run (e.g., "node", "python")
args: Array of arguments (e.g., ["path/to/server.js"])

For SSE/HTTP transport (remote servers):

url: Server URL (e.g., "http://localhost:3000/sse")
headers: Optional HTTP headers object

Common:

transport: Force transport type ("stdio", "sse", or "http"). Auto-detected if not specified.

Examples

List tools from a local MCP server:

{
  "command": "node",
  "args": ["/path/to/some-mcp-server/dist/server.js"]
}

Call a tool on a remote server:

{
  "url": "http://localhost:3000/sse",
  "tool_name": "search",
  "tool_args": {"query": "hello"}
}

Architecture

src/
├── server.ts     # MCP server exposing inspector tools
├── client.ts     # Client wrapper for inspecting other servers
└── transport.ts  # Transport factory (stdio, SSE, HTTP)

Why This Exists

The original MCP Inspector is a web-based UI + CLI combo spread across multiple projects. This consolidates the core functionality into a single, lean MCP server that an LLM can use to:

Develop and debug MCP servers iteratively
Test MCP server functionality without leaving the conversation
Explore what tools/resources/prompts an MCP server exposes

License

MIT

MCP Inspector as MCP Server