MCP & Connectors

How do you view and debug logs for MCP servers?

Last verified: July 2026 · 2 min read
QUICK ANSWER

In stdio MCP servers, route logs to stderr using console.error() instead of console.log(). In Claude Desktop, inspect logs at ~/Library/Logs/Claude/mcp.log to review JSON-RPC errors.

Log Locations

  • macOS Log File: ~/Library/Logs/Claude/mcp.log
  • Windows Log File: %APPDATA%\Claude\Logs\mcp.log

Ensure you write logs to standard error in your custom code:

console.error("Debugging database query result count: " + results.length);
Verified against: Claude Desktop v0.18.0

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