Anthropic

The 'Create a Text Completion' endpoint has been marked as 'Deprecated' in the navigation menu of Anthropic's API documentation. This signals an official deprecation of the legacy Text Completions API.

Anthropic added documentation for a new `server_tools` capability object in the Models API response, which reports whether a model supports web search and code execution tools. A separate top-level `code_execution` capability field is also described, indicating whether Claude can call other tools programmatically during code execution.

Anthropic has added Claude Haiku 5.5 as a new model to their lineup, replacing Claude Haiku 4.5 as the primary featured fast model. Claude Haiku 5.5 offers significantly improved specs including a 1M token context window, 128K max output, adaptive thinking, and pricing starting from $0.10/input MTok, with a retirement date no sooner than October 7, 2027.

Anthropic added documentation for a new `thinking.types.disabled` field in the Models API capabilities object, which indicates whether a model accepts `thinking: {type: "disabled"}` to turn off thinking mode. This clarifies API behavior around disabling thinking on models that support it.

Anthropic's Models API response now includes a `line` field that identifies which model line (e.g., 'opus') a model belongs to, enabling grouping of models in pickers and UIs. The field is `null` for models that belong to no line.

The documentation for the `anthropic-workspace-id` request header has been clarified to specify that a single-workspace API key will automatically run in its associated workspace when the header is omitted. This is a documentation clarification, not a behavior change.

Two new navigation sections—'Plugins' and 'Plugin Marketplaces'—have been added to the API reference sidebar, indicating new plugin-related endpoints are being introduced to the platform.

Anthropic has replaced Claude Sonnet 5 with Claude Sonnet 5.5 in the current model lineup. The new model shares the same pricing tier but has an updated model ID (`claude-sonnet-5-5`), an extended reliable knowledge cutoff (Jun 2026 vs Jan 2026), and a later retirement date (September 28, 2027 vs June 30, 2027).

Anthropic's model overview page now exposes an expanded 'Additional details' section showing training data cutoffs, retirement dates, and platform-specific model IDs (Amazon Bedrock, Google Cloud, Microsoft Foundry, Claude Platform on AWS) for all current models. No API surface was added or removed; this is a documentation enrichment.

Anthropic has introduced Claude Opus 5.5 as a new model, replacing Claude Opus 5 as the recommended default for most workloads. The new model features updated pricing ($4/$20 per MTok input/output vs $5/$25), 'Adaptive (always on)' thinking mode, 'medium' default effort, and an updated knowledge cutoff of June 2026.

The `Authorization` header is now the primary authentication method, with `x-api-key` reclassified as a 'legacy fallback' that is still supported but no longer required. Previously both headers were listed as equally valid alternatives (one required), but now `Authorization: Bearer <token>` is the preferred method for both API keys and WIF tokens.

Two minor additions to the navigation/UI: an 'Ask Docs' feature and a 'Parse Unverified' item added alongside the existing 'Unwrap' entry in the Webhooks section. No API contract changes were made.

Anthropic has added `anthropic-workspace-id` as a new request header that is required for multi-workspace API keys and optional for others. The documentation also introduces the concept of 'Key types' for API keys, expanding the authentication options available to developers.

Anthropic's models overview page has been reorganized with per-model detail pages added for Claude Fable 5, Opus 5, Sonnet 5, and Haiku 4.5, along with a restructured navigation. The comparison table now includes a 'Default effort' row and confirms all current models support tool use, but no model IDs, pricing, or API contracts have changed.

The navigation sidebar reorganized the 'Files' and 'Models' sections (moved out from under 'Skills'), and the pagination documentation was updated to explicitly document Skills API pagination behavior: GET /v1/skills and GET /v1/skills/{skill_id}/versions use the page/next_page scheme, with a has_more Boolean added when the skills-2025-10-02 beta header is included.

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; otherwise it uses the standard `page`/`next_page` scheme.

The API overview documentation now documents a new `anthropic-workspace-id` response header (prefixed `wrkspc_`) returned on most authenticated API responses, and expands the description of existing response headers (`request-id`, `anthropic-organization-id`) with more detail including example values and links to related guidance.

Claude Sonnet 5 pricing has been updated: the listed price changed from $3/$15 per MTok (input/output) to $2/$10 per MTok, and a footnote indicating this was 'introductory pricing through August 31, 2026' has been removed, suggesting the lower price is now the standard rate. Minor navigation/footer content was also added.

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.