Source Intelligence

DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

All of v2.1.75 Home All releases olderv2.1.74 v2.1.76newer
Claude Code v2.1.75

SendMessage Tool Redesigned

The SendMessage tool schema has been simplified from a discriminated union with type/recipient/content fields to a more intuitive to/message/summary format. Agents now use to: "<name>" for direct messages and to: "*" for broadcasts. Structured protocol messages (shutdown requests, plan approvals) are sent as objects in the message field. A backward-compatibility shim (backfillObservableInput) translates old-format calls.

Evidence

Simplified SendMessage schema (search for "Recipient: teammate name", 'to must be a bare teammate name or "*"')

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

See this entry in the whole of v2.1.75 →