Anthropic updates Python SDK with mid-conversation tool changes, session budgets, and advisor tool support

Anthropic released version 0.121.0 of the anthropic-sdk-python, which adds beta support for mid-conversation tool changes as of July 1, 2026. This feature allows developers to modify tools during an ongoing conversation, enabling more dynamic and adaptive interactions with the model.

The update introduces session budgets, providing a mechanism to manage and constrain usage costs within a session. It also adds support for the advisor tool, which can assist in guiding or monitoring model behavior during execution.

Version 0.121.0 includes pinned inference location, allowing users to specify a preferred geographic region for inference, and skills auto-loading from GitHub, which streamlines the integration of external skills or tools into the model's workflow.

The release removes support for the retired Claude Opus 4.1 models, aligning the SDK with Anthropic's current model lineup and discontinuing legacy compatibility.

Documentation updates accompany the release, including small updates to descriptions and revisions to documentation strings to reflect new and updated features.

Dependency management was also addressed, with changes to ensure all dependencies include major version constraints to improve stability and predictability in deployment environments.