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Logging lets your server send debug/info/warning/error messages to MCP clients while handling a request. This is helpful for visibility during tool execution and for debugging. Note: Clients decide how (or whether) to display these logs.

Basic usage

Log levels

Example: Data pipeline

Example: Batch processing

Structured logging

Pass structured fields using data=:
Tip: Avoid using the key "msg" inside data—Dedalus MCP uses "msg" internally for the main message text.
Last modified on June 30, 2026