2026-07-09 06:55 UTC · anthropic/api-release-notes · live page
Summary by fallback. It may be wrong; the diff below is what actually changed. Raw: 7422302fe3-anthropic-api-release-notes.diff · commit 7422302fe3
diff --git a/snapshots/anthropic/api-release-notes.md b/snapshots/anthropic/api-release-notes.mdindex a858e93..b1ea964 100644--- a/snapshots/anthropic/api-release-notes.md+++ b/snapshots/anthropic/api-release-notes.md@@ -5,4 +5,17 @@ For release notes on Claude Apps, see the Release notes for Claude Apps in the C For updates to Claude Code, see the complete CHANGELOG.md in the `claude-code` repository. +### July 1, 2026++- We've restored access to Claude Fable 5 and Claude Mythos 5. See our statement for more information.++### June 30, 2026++- We've launched Claude Sonnet 5 (`claude-sonnet-5`), the next generation of our Sonnet model family, at introductory pricing of $2 / $10 per MTok through August 31, 2026 (standard $3 / $15 thereafter). Claude Sonnet 5 supports a 1M token context window, 128k max output tokens, and the same set of tools and platform features as Claude Sonnet 4.6, except Priority Tier, which is not available on Claude Sonnet 5. Three behavior changes apply when migrating: adaptive thinking is now on by default; manual extended thinking (`thinking: {type: "enabled", budget_tokens: N}`) is removed and returns a 400 error (it was deprecated on Sonnet 4.6); and setting sampling parameters (`temperature`, `top_p`, `top_k`) to non-default values returns a 400 error. Claude Sonnet 5 also uses a new tokenizer that produces approximately 30% more tokens for the same text. The exact increase depends on the content and workload shape. See What's new in Claude Sonnet 5 for details and migration guidance. For behavioral differences and model-specific prompting patterns, see Prompting Claude Sonnet 5.+- Claude Managed Agents session event streams now support event deltas. Opt in with the `event_deltas[]` query parameter on `GET /v1/sessions/{session_id}/events/stream`. The `event_start` and `event_delta` events preview an agent message's text as it's generated, before the complete `agent.message` event arrives.+- Listing sessions for Claude Managed Agents now supports backward pagination. `GET /v1/sessions` returns a `prev_page` cursor alongside `next_page`; pass it as the `page` parameter to return to the previous page. See Pagination.+- When creating a Claude Managed Agents session, you can now override the agent's configuration for that session. Pass `agent` with `type: "agent_with_overrides"` to replace the model, system prompt, tools, MCP servers, or skills for a single session. The agent itself is unchanged.+- Claude Managed Agents vaults now support an `injection_location` setting on environment variable credentials (the Environment variable tab). It controls whether the credential's value is substituted, at egress, into the agent's outbound request headers, the request body, or both.+- Webhooks for Claude Managed Agents now cover the agent, deployment, and deployment run lifecycle. You can react to a newly published agent version, a paused deployment, or a failed scheduled run without polling. See the Agent events, Deployment events, and Deployment run events tabs in Subscribe to webhooks.+ ### June 29, 2026 @@ -17,4 +30,8 @@ For updates to Claude Code, see the complete CHANGELOG.md in the `claude-code` r - We've deprecated fast mode for Claude Opus 4.7, with removal on July 24, 2026. After removal, requests to `claude-opus-4-7` with `speed: "fast"` will return an error. Migrate to fast mode for Claude Opus 4.8. Read more in Fast mode. +### June 22, 2026++- MCP tunnels (research preview): the management API moved from `/v1/organizations/tunnels` on the Admin API to `/v1/tunnels` on the Claude API. The new surface uses the `anthropic-beta: mcp-tunnels-2026-06-22` header and the `workspace:manage_tunnels` WIF scope. The previous surface remains available during a migration window. See the Tunnels API reference.+ ### June 18, 2026 @@ -37,10 +54,10 @@ For updates to Claude Code, see the complete CHANGELOG.md in the `claude-code` r - We've launched Claude Fable 5 (`claude-fable-5`), our most capable widely released model, alongside Claude Mythos 5 (`claude-mythos-5`) for Project Glasswing participants. Both models support a 1M token context window by default, 128k max output tokens, and always-on adaptive thinking. See Introducing Claude Fable 5 and Claude Mythos 5 for capabilities, API changes, and availability.-- Claude Fable 5 and Claude Mythos 5 use the tokenizer introduced with Claude Opus 4.7. Compared to models before Claude Opus 4.7, the same text produces roughly 30% more tokens. Use the token counting API with `model: "claude-fable-5"` to measure your prompts under the new tokenizer.+- Claude Fable 5 and Claude Mythos 5 use the tokenizer introduced with Claude Opus 4.7. Compared to models before Claude Opus 4.7, the same text produces roughly 30% more tokens. The exact increase depends on the content and workload shape. Use the token counting API with `model: "claude-fable-5"` to measure your prompts under the new tokenizer. - Claude Fable 5 runs safety classifiers on requests and during response generation. When a classifier declines a request, the Messages API returns `stop_reason: "refusal"`. You are not billed for a request refused before any output is generated. An opt-in `fallbacks` parameter (in beta on the Claude API and Claude Platform on AWS; not supported on the Message Batches API) re-runs refused requests on another model, billed at the fallback model's rates. See Handling stop reasons. - The `stop_details.category` field on refusal responses now includes `"reasoning_extraction"` on Claude Fable 5, returned when a request is blocked under Anthropic's Terms of Service restrictions on reverse engineering or duplicating model outputs. The existing `"cyber"` and `"bio"` categories are unchanged. No beta header is required. - On Claude Fable 5 and Claude Mythos 5, adaptive thinking is the only thinking mode: `thinking: {"type": "disabled"}` is not supported, and manual extended thinking budgets and assistant prefill are not supported (both return a 400 error). See Migrating from Claude Mythos Preview to Claude Mythos 5. - On Claude Fable 5 and Claude Mythos 5, `thinking.display` defaults to `"omitted"`, the same as Claude Opus 4.8, Claude Opus 4.7, and Claude Mythos Preview; set `display: "summarized"` to receive readable thinking summaries. The raw chain of thought is never returned; pass thinking blocks back unchanged in multi-turn conversations on the same model. See Thinking output on Claude Fable 5 and Claude Mythos 5.-- Claude Fable 5 requires 30-day data retention on the Claude API and is not available under zero data retention. See Model-specific data retention requirements.+- Claude Fable 5 requires 30-day data retention and is not available under zero data retention. See Model-specific data retention requirements. - Claude Managed Agents now supports scheduled deployments, letting you run sessions on a cron schedule without managing your own scheduler. - Claude Managed Agents vaults now support environment variable credentials, so you can securely inject secrets into the agent's sandbox for CLIs, SDKs, and other services that authenticate through environment variables.@@ -200,5 +217,5 @@ For updates to Claude Code, see the complete CHANGELOG.md in the `claude-code` r ### February 7, 2026 -- We've launched fast mode in research preview for Opus 4.6, providing significantly faster output token generation via the `speed` parameter. Fast mode is up to 2.5x as fast at premium pricing. Interested customers should join the waitlist.+- We've launched fast mode in research preview for Opus 4.6, providing significantly faster output token generation through the `speed` parameter. Fast mode is up to 2.5x as fast at premium pricing. Interested customers should join the waitlist. ### February 5, 2026@@ -217,5 +234,5 @@ For updates to Claude Code, see the complete CHANGELOG.md in the `claude-code` r ### January 12, 2026 -- `console.anthropic.com` now redirects to `platform.claude.com`. The Claude Console has moved to its new home as part of our Claude brand consolidation. Existing bookmarks and links will continue working via automatic redirect. For more details, see the September 16, 2025 announcement.+- `console.anthropic.com` now redirects to `platform.claude.com`. The Claude Console has moved to its new home as part of our Claude brand consolidation. Existing bookmarks and links will continue working through an automatic redirect. For more details, see the September 16, 2025 announcement. ### January 5, 2026@@ -265,5 +282,5 @@ For updates to Claude Code, see the complete CHANGELOG.md in the `claude-code` r - We've launched Agent Skills (`skills-2025-10-02` beta), a new way to extend Claude's capabilities. Skills are organized folders of instructions, scripts, and resources that Claude loads dynamically to perform specialized tasks. The initial release includes: - Anthropic-managed Skills: Pre-built Skills for working with PowerPoint (.pptx), Excel (.xlsx), Word (.docx), and PDF files- - Custom Skills: Upload your own Skills via the Skills API (`/v1/skills` endpoints) to package domain expertise and organizational workflows+ - Custom Skills: Upload your own Skills through the Skills API (`/v1/skills` endpoints) to package domain expertise and organizational workflows - Skills require the code execution tool to be enabled - Learn more in Agent Skills and API reference@@ -422,5 +439,5 @@ For updates to Claude Code, see the complete CHANGELOG.md in the `claude-code` r ### February 27th, 2025 -- We've added URL source blocks for images and PDFs in the Messages API. You can now reference images and PDFs directly via URL instead of having to base64-encode them. Learn more in Vision and PDF support.+- We've added URL source blocks for images and PDFs in the Messages API. You can now reference images and PDFs directly through a URL instead of having to base64-encode them. Learn more in Vision and PDF support. - We've added support for a `none` option to the `tool_choice` parameter in the Messages API that prevents Claude from calling any tools. Additionally, you're no longer required to provide any `tools` when including `tool_use` and `tool_result` blocks. - We've launched an OpenAI-compatible API endpoint, allowing you to test Claude models by changing just your API key, base URL, and model name in existing OpenAI integrations. This compatibility layer supports core chat completions functionality. Learn more in OpenAI SDK compatibility.