Anthropic

Category: ai

8 changes tracked

Monitored sources:

changelog · every 1hdocs · every 1h

SDK packages:

@anthropic-ai/sdkanthropicanthropicgithub.com/anthropics/anthropic-sdk-gocom.anthropic:anthropic-javaanthropic

Last polled: 9/16/2026, 3:00:01 PM

Change History

behavioralmedium82% confidence

Anthropic has updated the authentication header documentation to promote `Authorization: Bearer <token>` as the primary authentication method, demoting `x-api-key` to a 'legacy fallback' that is still supported. The required/optional status of these headers has been inverted compared to the previous documentation.

Migration: Begin migrating from `x-api-key` to `Authorization: Bearer <api-key>` header for future-proofing, though `x-api-key` remains supported for now. SDK users are unaffected as the SDK handles header management automatically.
header:x-api-keyheader:Authorization

9/3/2026

new_featureinfo55% confidence

Two new navigation/sidebar items were added to the API docs: 'Parse' and 'Unverified' (appearing under the Webhooks section), and an 'Ask Docs' UI element was added to the documentation interface. These appear to be new endpoint entries and a docs assistant feature.

endpoint:Webhooks / Parseendpoint:Webhooks / Unverified

8/28/2026

new_featuremedium82% confidence

Anthropic has added `anthropic-workspace-id` as a new request header, required for multi-workspace API keys and optional for others. Additionally, API key creation now supports selecting a key type, and the workspace management guidance has been updated.

Migration: If your API key is scoped to multiple workspaces, you must now pass the `anthropic-workspace-id` request header to select the target workspace. Single-workspace keys are unaffected but may optionally include it. Review the new 'Key types' documentation when creating new API keys.
header:anthropic-workspace-idendpoint:POST /v1/oauth/token

8/28/2026

new_featureinfo82% confidence

Anthropic has added new models Claude Fable 5 and Claude Mythos 5 to their lineup, with Claude Fable 5 becoming the most capable widely released model and Claude Mythos 5 available via invitation-only Project Glasswing. The models page has also been significantly restructured with individual model pages and updated navigation.

Migration: Update your model IDs to use 'claude-fable-5' for the new top-tier model or 'claude-opus-5' for complex agentic/enterprise work. Claude Fable 5 is available on Claude API, Amazon Bedrock, Google Cloud, and Microsoft Foundry starting June 9, 2026. No breaking changes to existing model IDs detected.
model:claude-fable-5model:claude-mythos-5model:claude-mythos-previewmodel:claude-opus-5model:claude-sonnet-5

8/24/2026

Effective: 6/9/2026

new_featureinfo82% confidence

Anthropic added documentation clarifying pagination behavior for the Skills API endpoints (`GET /v1/skills` and `GET /v1/skills/{skill_id}/versions`), noting they use the `page`/`next_page` cursor scheme and that requests with the `skills-2025-10-02` beta header also return a `has_more` boolean. The navigation sidebar also reorganized the order of Files and Models sections.

Migration: If using the Skills API list endpoints, include the `skills-2025-10-02` beta header to receive the additional `has_more` field alongside `next_page` in paginated responses.
endpoint:GET /v1/skillsendpoint:GET /v1/skills/{skill_id}/versionsheader:skills-2025-10-02param:has_more

8/20/2026

new_featureinfo82% confidence

The Files API and Skills API have been promoted from Beta to General Availability. Additionally, the Files API pagination behavior has been clarified: it uses the `after_id`/`before_id` scheme only when the `files-api-2025-04-14` beta header is included; without the header, `GET /v1/files` uses the standard `page`/`next_page` cursor scheme.

Migration: If you use the Files API, note that pagination behavior depends on whether you include the `files-api-2025-04-14` beta header. Include it to use `after_id`/`before_id` pagination, or omit it to use the default `page`/`next_page` scheme. No changes needed if you are already using Skills API.
endpoint:GET /v1/filesendpoint:POST /v1/filesendpoint:POST /v1/skillsendpoint:GET /v1/skillsheader:files-api-2025-04-14param:after_idparam:before_idparam:page

8/19/2026

new_featureinfo92% confidence

Anthropic added a new `anthropic-workspace-id` response header that returns the workspace ID associated with the API key or access token used in the request. The documentation for the existing `request-id` and `anthropic-organization-id` headers was also expanded with more detail.

Migration: No action required; optionally read the new `anthropic-workspace-id` response header to identify which workspace an API response resolved to, which can be useful for multi-workspace setups.
header:anthropic-workspace-idheader:request-idheader:anthropic-organization-id

8/12/2026

breakinghigh90% confidence

The Sessions API streaming endpoint path has changed from `GET /v1/sessions/{id}/stream` to `GET /v1/sessions/{id}/events/stream`. This is a breaking rename of an existing beta endpoint URL.

Migration: Update any hardcoded or constructed URLs for session streaming from `/v1/sessions/{id}/stream` to `/v1/sessions/{id}/events/stream`. Check SDK versions for updated path support.
endpoint:GET /v1/sessions/{id}/streamendpoint:GET /v1/sessions/{id}/events/stream

8/3/2026

Get alerts when Anthropic changes affect your code

Connect your GitHub repos and Breakwatch will map your Anthropic usage and alert you about relevant changes.

Get started for free