MCP Inspector

Test MCP connections and debug protocol issues

The MCP Inspector is a free interactive tool for testing MCP server connections. Point it at any MCP endpoint, authenticate, and execute MCP actions – initialize, list tools, call tools, list resources, list prompts. Every request and response is logged with timestamps and latency.

Interface

The inspector has two panels:

Left panel – configuration:

  1. Quick Start: Select from your saved DataGrout servers (auto-fills URL and auth) or choose a pre-configured example
  2. MCP Server URL: The MCP endpoint to connect to. Auto-appends /mcp if missing
  3. Authentication: None, Bearer Token, Basic Auth, or OAuth 2.0
  4. Action: Choose what to do:
    • Initialize (establish session with the server)
    • List Tools
    • Call Tool (shows a tool selector and JSON parameters field)
    • List Resources
    • List Prompts
  5. Execute Request: Send the action

Right panel – response log:

Each response shows a timestamp, action badge, latency, and the formatted JSON result. For List Tools, the response renders as an expandable accordion view (toggle to raw JSON). Each entry has Copy JSON and Export cURL buttons.

A connection status badge shows whether the session is initialized. A rate limit indicator shows remaining calls per hour.

Getting Started

Test a DataGrout Server

  1. Open the MCP Inspector
  2. Click Your Servers in Quick Start and select a server
  3. The URL and authentication fill automatically
  4. Click Execute Request with the Initialize action selected
  5. Once initialized, switch the action to List Tools and execute again
  6. Browse the tool list to verify your integrations are connected

Test an External MCP Server

  1. Enter the server URL (e.g. http://localhost:3000/mcp)
  2. Select the appropriate authentication method
  3. Initialize, then list tools or call a tool

Call a Tool

  1. Initialize the session first
  2. Switch the action to Call Tool
  3. Select a tool from the dropdown (populated after List Tools)
  4. Enter arguments as JSON in the parameters field
  5. Execute and inspect the response

MCP vs JSONRPC

MCP uses JSON-RPC 2.0 over Server-Sent Events (SSE). It requires an initialization handshake that establishes a persistent session. The server can push events to the client.

If you want stateless HTTP POST testing without session management, use the JSONRPC Inspector instead.

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