MCP ConfigsApr 1, 2026·2 min read

MCP Inspector — Debug MCP Servers Visually

Official MCP Inspector for testing and debugging MCP servers. 9.3K+ stars. Web UI, tool/resource/prompt inspection, request testing.

MCP Hub
MCP Hub · Community
TL;DR
MCP Inspector is the official web-based tool for connecting to, inspecting, and testing MCP servers with a visual interface for tools, resources, and prompts.
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What it is

MCP Inspector is the official visual testing and debugging tool for Model Context Protocol (MCP) servers. It provides a web UI where you connect to any MCP server and inspect its tools, resources, and prompts. You can test individual tool calls, view request/response payloads, and debug connection issues without writing code.

MCP Inspector targets MCP server developers and anyone integrating MCP tools into AI agents. It serves as the debugging companion during development, letting you verify server behavior before connecting it to Claude Code or other agents.

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How it saves time or tokens

Without MCP Inspector, debugging MCP servers requires reading logs, crafting JSON requests manually, or connecting a full AI agent to test each tool. MCP Inspector provides instant visual feedback: see all available tools, click to test them, and inspect the responses. This shortens the debug cycle from minutes to seconds.

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How to use

  1. Run MCP Inspector with npx @modelcontextprotocol/inspector.
  2. Open the web UI at http://localhost:6274.
  3. Connect to your MCP server and inspect tools, resources, and prompts.
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Example

# Start MCP Inspector
npx @modelcontextprotocol/inspector

# Opens web UI at http://localhost:6274
# Connect to your MCP server (stdio or HTTP)

# Example: inspect a filesystem MCP server
npx @modelcontextprotocol/inspector -- npx @modelcontextprotocol/server-filesystem /tmp
FeatureDescription
Tool inspectionList all tools with schemas
Request testingCall tools with custom parameters
Resource browsingView available resources
Prompt listingInspect prompt templates
Connection debugDiagnose connection issues
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Related on TokRepo

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Common pitfalls

  • MCP Inspector connects via stdio by default. If your server uses HTTP transport, configure the connection type in the UI.
  • The inspector runs on port 6274. Ensure no other service occupies this port before starting.
  • MCP Inspector shows the raw MCP protocol. Understanding the MCP specification helps interpret the tool schemas and request formats.

Frequently Asked Questions

What is MCP?+

MCP (Model Context Protocol) is a standard for connecting AI agents to external tools and data sources. MCP servers expose tools, resources, and prompts that AI agents can call. MCP Inspector helps you debug these servers.

Can I test any MCP server with the inspector?+

Yes. MCP Inspector connects to any MCP-compliant server regardless of implementation language. It supports stdio and HTTP transport modes.

Do I need to install MCP Inspector globally?+

No. Use npx to run it directly without global installation. Each invocation downloads the latest version automatically.

Can MCP Inspector modify data through tool calls?+

Yes. When you test a tool in the inspector, it executes the actual tool call on the server. Be careful when testing tools that modify data (write, delete) on production servers.

Is MCP Inspector official?+

Yes. MCP Inspector is maintained under the @modelcontextprotocol npm scope, the same organization that maintains the MCP specification and reference servers.

Citations (3)
Related on TokRepo
Chrome MCPGitHub MCPFeatured workflows
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