anthropics/anthropic-sdk-python v1.9.0

on GitHub

1.9.0 (2026-09-28)

Full Changelog: v1.8.0...v1.9.0

Features

• api: add between_tools thinking type (a9a577d)
• api: add claude-sonnet-5-5 (a5a25e9)
• api: add include_inherited and source to workspace rate limits (0bf4af8)
• api: add typed event type values to the Managed Agents events list filter (1b82cd9)
• api: cache diagnostics GA — diagnostics on Message / MessageCreateParams (22062b8)
• tools: optionally run tool calls while the reply streams (26d0812)

Bug Fixes

• client: send no placeholder filename for unnamed file uploads (9e9709d)
• helpers: degrade between_tools thinking to disabled on fallback hops (#952) (a3834d4)
• messages: accept diagnostics in stream() and parse() (#929) (fad840c)

Chores

• api: list the known model ids first in the Model types (e5a082a)
• ci: choose the CI runner by repository (39ccf62)
• client: stop sending beta header from parse and tool runner (#907) (1428100)
• docs: clarify that stream: true returns the raw event stream (82918fa)
• docs: make Managed Agents actor descriptions resource-neutral (34ef524)
• docs: restore the research-preview notice on the Dream type (f03e32e)

Documentation

• add field docstring spacing rule to CLAUDE.md (e5c35f4)
• api: prefer each field's own description over its shared type's (d79a2e7)
• claude.md: add function body spacing rule (3174f8f)
• list importable type names in api.md (56a42ab)