MCP Inspector

Inspect MCP servers you choose — call tools, browse resources, and watch JSON-RPC traffic.

MCP Inspector is a side-panel developer tool for building, testing, and debugging Model Context Protocol (MCP) servers. Connect to your own server (Streamable HTTP, legacy SSE, or WebSocket), or click Connect on the built-in demo to test the UI instantly without local setup. KEY FEATURES: • Inspect Server Details: View protocol versions, instructions, and reported capabilities at a glance. • Interactive Tool Execution: Call tools via dynamic forms automatically generated from JSON Schemas. • Resources & Prompts: Read server resources, inspect URI templates, supply prompt arguments, and preview rendered outputs. • Traffic Inspector: Monitor JSON-RPC frames in real time with latency metrics, payload size, filtering, and one-click copy. • Integrated OAuth 2.1: Handles authorization code + PKCE in Chrome’s native auth window on 401 responses, storing tokens locally per server. OPTIONAL & ADVANCED CAPABILITIES: • Natural Language Testing (Ask): Add your Gemini API key to test server tools interactively. The extension will not send prompts or tool definitions anywhere until you supply a key and opt in. • Page Mode (Experimental): Inspect WebMCP tools on the active tab (document.modelContext) with explicit site permission. Requires Chrome 150+ and chrome://flags/#enable-webmcp-testing. • Stdio Transport: Connect to local Node.js / npx servers via an optional native messaging host (configured separately; not required for standard web transports). PRIVACY & PERMISSIONS: • Server mode runs on Chrome 116+ without injecting scripts into websites. • Contains zero ads, trackers, analytics, or affiliate links.