mcp.zig

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MCP Inspector ​

The MCP Inspector is an interactive developer tool for testing and debugging MCP servers.

Getting started ​

Prerequisites

The MCP Inspector is a Node.js tool. You must have Node.js installed to run it, even though your project is in Zig.

The Inspector runs directly through npx without requiring installation:

bash
npx @modelcontextprotocol/inspector <command>

Inspecting local servers ​

To inspect servers locally developed (e.g., your Zig MCP server), you can run:

bash
npx @modelcontextprotocol/inspector <your-server-command> [args...]
# Example for a Zig server
npx @modelcontextprotocol/inspector zig build run-server

Features ​

The Inspector interface provides several features:

  • Server connection pane: Select transport and customize command-line arguments.
  • Resources tab: List resources, show metadata, inspect content, and test subscriptions.
  • Prompts tab: Display templates, arguments, and test prompts with custom inputs.
  • Tools tab: List tools, show schemas, and test tool execution.
  • Notifications pane: View logs and notifications received from the server.

Best Practices ​

  • Iterative testing: Make server changes, rebuild, reconnect Inspector, and test.
  • Monitor messages: Watch the log pane to see JSON-RPC traffic.
  • Test edge cases: Try invalid inputs or missing arguments to verify error handling.