31 pages for fallbacks.

Or, for the model with the same capabilities and no access approval requirement: Claude Developer Platform · in the page about-claude/models/migration-guide …run refused requests on another model automatically, pass the opt-in `fallbacks` parameter, which is in beta on the Claude API. The parameter is not available on the Message Batches API or on Amazon B… claude-api-skill Claude Developer Platform · in the page agents-and-tools/agent-skills/claude-api-skill …when the target is Claude Fable 5 or Claude Opus 5 (the server-side `fallbacks` parameter, typically in its `"default"` mode, the SDK refusal-fallback middleware, or a fallback-credit retry), and upd… Beta Claude Developer Platform · in the page api/beta …odels: array of string or null` Model IDs this model accepts as `fallbacks[i].model` on the Messages API. An empty list means the `fallbacks` parameter is not supported for this model as primary.… Messages Claude Developer Platform · in the page api/beta/messages …endered into the prompt; not validated against the request's `fallbacks` chain or top-level `model`. Echo the assistant turn back verbatim, including this block in its origina… Batches Claude Developer Platform · in the page api/beta/messages/batches …red into the prompt; not validated against the request's `fallbacks` chain or top-level `model`. Echo the assistant turn back verbatim, including this block in its… Create a Message Batch Claude Developer Platform · in the page api/beta/messages/batches/create …red into the prompt; not validated against the request's `fallbacks` chain or top-level `model`. Echo the assistant turn back verbatim, including this block in its… Count tokens in a Message Claude Developer Platform · in the page api/beta/messages/count_tokens …endered into the prompt; not validated against the request's `fallbacks` chain or top-level `model`. Echo the assistant turn back verbatim, including this block in its origina… Create a Message Claude Developer Platform · in the page api/beta/messages/create …endered into the prompt; not validated against the request's `fallbacks` chain or top-level `model`. Echo the assistant turn back verbatim, including this block in its origina… Models Claude Developer Platform · in the page api/beta/models …odels: array of string or null` Model IDs this model accepts as `fallbacks[i].model` on the Messages API. An empty list means the `fallbacks` parameter is not supported for this model as primary.… List Models Claude Developer Platform · in the page api/beta/models/list …odels: array of string or null` Model IDs this model accepts as `fallbacks[i].model` on the Messages API. An empty list means the `fallbacks` parameter is not supported for this model as primary.… Get a Model Claude Developer Platform · in the page api/beta/models/retrieve …odels: array of string or null` Model IDs this model accepts as `fallbacks[i].model` on the Messages API. An empty list means the `fallbacks` parameter is not supported for this model as primary.… claude-in-amazon-bedrock Claude Developer Platform · in the page build-with-claude/claude-in-amazon-bedrock …Usage and Cost) * Claude Managed Agents * Server-side fallback (the [`fallbacks` parameter](https://platform.claude.com/docs/en/build-with-claude/refusals-and-fallback#server-side-fallback); use the [… claude-in-microsoft-foundry Claude Developer Platform · in the page build-with-claude/claude-in-microsoft-foundry …API * Models API * Message Batches API * Server-side fallback (the [`fallbacks` parameter](https://platform.claude.com/docs/en/build-with-claude/refusals-and-fallback#server-side-fallback); use the [… claude-on-amazon-bedrock-legacy Claude Developer Platform · in the page build-with-claude/claude-on-amazon-bedrock-legacy …Usage and Cost) * Claude Managed Agents * Server-side fallback (the [`fallbacks` parameter](https://platform.claude.com/docs/en/build-with-claude/refusals-and-fallback#server-side-fallback); use the [… claude-on-vertex-ai Claude Developer Platform · in the page build-with-claude/claude-on-vertex-ai …Usage and Cost) * Claude Managed Agents * Server-side fallback (the [`fallbacks` parameter](https://platform.claude.com/docs/en/build-with-claude/refusals-and-fallback#server-side-fallback); use the [… fallback-credit Claude Developer Platform · in the page build-with-claude/fallback-credit …try's sake: * **`server-side-fallback-*`:** a retry must drop the `fallbacks` parameter, and dropping this header along with it does not cause a mismatch. * **`fallback-credit-*`:** keep this hea… overview Claude Developer Platform · in the page build-with-claude/overview …s, the API runs the next model in the chain on the same request. The `fallbacks` parameter is not available in the Message Batches API. | Not ZDR eligible\*… claude-prompting-best-practices Claude Developer Platform · in the page build-with-claude/prompt-engineering/claude-prompting-best-practices …ic isn't self-evident. - Defensive coding: Don't add error handling, fallbacks, or validation for scenarios that can't happen. Trust internal code and framework guarantees. Only validate at system bo… prompting-claude-fable-5 Claude Developer Platform · in the page build-with-claude/prompt-engineering/prompting-claude-fable-5 …traction and half-finished implementations. Don't add error handling, fallbacks, or validation for scenarios that cannot happen. Trust internal code and framework guarantees. Only validate at system b… refusals-and-fallback Claude Developer Platform · in the page build-with-claude/refusals-and-fallback …-to-end example. The simplest setup, in beta on the Claude API: set `fallbacks` to `"default"`, and the API retries a declined request on the fallback model Anthropic recommends for its refusal categ… introducing-claude-fable-5-and-claude-mythos-5 Claude Developer Platform · in the page models/fable-5/introducing-claude-fable-5-and-claude-mythos-5 …e model. There are three ways to retry: * **Server-side:** Pass the `fallbacks` parameter to have the API retry for you, using its `"default"` mode for Anthropic's recommended models or naming your o… Or, for the model with the same capabilities and no access approval requirement: Claude Developer Platform · in the page models/fable-5/migration-guide …run refused requests on another model automatically, pass the opt-in `fallbacks` parameter, which is in beta on the Claude API. The parameter is not available on the Message Batches API or on Amazon B… overview Claude Developer Platform · in the page models/fable-5/overview …andle classifier refusals and retry on another Claude model with the `fallbacks` parameter. </Card> <Card title="Adaptive thinking" icon="brain" href="https://platform.claude.com/docs/en/build-wi… Opus migration Claude Developer Platform · in the page models/opus-5/migration-guide …ct; start at 64k tokens and tune from there. 2. **Consider automatic fallbacks:** Claude Opus 5 ships with cybersecurity safety classifiers whose cyber-category refusals can fall back to Claude Opus… whats-new-opus-5 Claude Developer Platform · in the page models/opus-5/whats-new-opus-5 …ystem-messages#mid-conversation-tool-changes) for usage. ### Default fallbacks mode The `fallbacks` parameter supports a new `"default"` mode, which applies Anthropic's recommended fallback models b… overview Claude Developer Platform · in the page release-notes/overview …rsation-tool-changes-2026-07-01` beta header in your requests. * The `fallbacks` parameter now supports a `"default"` mode, which applies Anthropic's recommended fallback models by refusal category. S… Error reference Claude Code CLI · in the page errors …o [reviewing every tracked file](/docs/en/ultrareview#diff-limits-and-fallbacks) instead of refusing. You see this refusal when the base branch can't be found at all, when Claude Code can't verify tha… Customize your status line Claude Code CLI · in the page statusline …first API response completes * Handle null values in your script with fallbacks such as `// 0` in jq * Restart Claude Code if values remain empty after multiple messages **Context percentage shows un… Find bugs with ultrareview Claude Code CLI · in the page ultrareview …hen run `/code-review ultra <PR-number>`. </Tip> ### Diff limits and fallbacks Ultrareview checks the diff before any review work runs and tells you when it can't review it as-is: * **Diff too larg… Blend your MCP App with Claude's theme Claude Documentation · in the page connectors/building/mcp-apps/transparent-theming …Once the variables are on `:root`, reference them directly. Provide fallbacks so the widget is still readable when rendered outside a host: ```css theme={null} body { font-family: var(--font-sans… Authorization Model Context Protocol · in the page specification/2025-03-26/basic/authorization …erver, regardless of any path components in the MCP server URL. #### Fallbacks for Servers without Metadata Discovery For servers that do not implement OAuth 2.0 Authorization Server Metadata, clien…