Diagnose MCP server issues in seconds
MCP clients give you 'connection failed' and nothing else. MCP Debugger sends the same JSON-RPC initialize handshake that Claude Desktop uses, discovers available tools, measures latency, and tells you exactly what's wrong and how to fix it.
Sends a JSON-RPC initialize request with protocol version 2025-03-26 — the same handshake Claude Desktop and other production MCP clients perform.
Sends a tools/list request and reports every tool the server exposes with names and descriptions. Catches servers with no tools registered.
Measures round-trip time with severity levels: under 2s is healthy, 2-5s is moderate (cold start), over 5s is a warning.
Maps HTTP 401 to auth failures, 404 to wrong path, timeouts to standby not enabled, DNS errors to typos. Every issue gets a specific root cause.
Not just 'something's wrong' but 'check that usesStandbyMode: true is set in actor.json' or 'verify the actor has been run at least once to warm up standby.'
Handles both standard JSON responses and multiline SSE-like formats used by StreamableHTTPServerTransport. Parses whatever your server sends.
{
"url": "https://ryanclinton--counterparty-due-diligence-mcp.apify.actor/mcp",
"status": "healthy",
"connectionSuccess": true,
"latencyMs": 1200,
"transport": "streamable-http",
"protocolVersion": "2025-03-26",
"serverName": "counterparty-due-diligence-mcp",
"toolCount": 3,
"tools": [
{ "name": "screen_counterparty", "description": "Screen a counterparty for risk" },
{ "name": "deep_dive", "description": "Deep investigation of an entity" },
{ "name": "network_analysis", "description": "Analyze corporate connections" }
],
"issues": [],
"suggestions": []
}Connect your Apify token and enter the actor ID
The tool runs the actor on your account and analyzes the output
Get a detailed report with actionable fixes — results cached for free