39 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 …laude Opus 5.5, Claude Opus 5, or Claude Sonnet 5.5 (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 …dered 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 ori… Batches Claude Developer Platform · in the page api/beta/messages/batches …d 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 …d 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 …dered 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 ori… Create a Message Claude Developer Platform · in the page api/beta/messages/create …dered 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 ori… 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.… Before Claude Developer Platform · in the page api/migration-2026-10-21 …e()` * `responseValidation()`, `timeout()`, `followRedirects()`, `fallbackState()`, and `openTelemetry()` on `RequestOptions`, which were `getResponseValidation()`, `getTimeout()`, `getFollowRedir… Message Batches API Claude Developer Platform · in the page build-with-claude/batch-processing …| | `fallbacks` ([Server-side fallback](https://platform.claude.com/docs/en/build-with-claude/refusals-and-fallback#server-side-fallbac… 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 [… google-managed Claude Developer Platform · in the page build-with-claude/claude-models-on-google-cloud/google-managed …ost API * **Claude Managed Agents** * **Server-side fallback:** The [`fallbacks` parameter](https://platform.claude.com/docs/en/build-with-claude/refusals-and-fallback#server-side-fallback) Instead o… 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 [… 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… fast-mode Claude Developer Platform · in the page build-with-claude/fast-mode …orm.claude.com/docs/en/manage-claude/usage-cost-api). ## Retries and fallbacks ### Automatic retries The SDK automatically retries fast mode `429` errors up to 2 times by default (configurable with… 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 …ld-with-claude/claude-models-on-google-cloud/anthropic-managed): set `fallbacks` to `"default"`, and the API retries a declined request on the fallback model Anthropic recommends for its refusal categ… Or, for Claude Mythos 5.1, which offers the same capabilities to verified organizations: Claude Developer Platform · in the page models/fable-5-1/migration-guide …l_addition` or `tool_removal` blocks can't be turn-scoped. 3. **Use `fallbacks: "default"` for refusals:** Keep handling `stop_reason: "refusal"` and reading `stop_details.category` before response c… whats-new-fable-5-1 Claude Developer Platform · in the page models/fable-5-1/whats-new-fable-5-1 …aude/refusals-and-fallback#client-side-fallback), or your own retry. `fallbacks: "default"` (beta) retries a declined request on the model Anthropic recommends for that category. The permitted fallbac… 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> </CardGroup> ## Reference <CardGroup cols={3}> <Card title="System prompt" icon="text" href="h… whats-new-opus-5-5 Claude Developer Platform · in the page models/opus-5-5/whats-new-opus-5-5 …cs/en/build-with-claude/refusals-and-fallback#server-side-fallback) (`fallbacks: "default"`, in beta, retries on the model Anthropic recommends for that category), the [SDK middleware](https://platfor… migration-guide Claude Developer Platform · in the page models/sonnet-5-5/migration-guide …cs/en/build-with-claude/refusals-and-fallback#server-side-fallback) (`fallbacks: "default"`), in beta on the Claude API and on [Claude Models on Google Cloud (Anthropic managed)](https://platform.clau… whats-new-sonnet-5-5 Claude Developer Platform · in the page models/sonnet-5-5/whats-new-sonnet-5-5 …cs/en/build-with-claude/refusals-and-fallback#server-side-fallback) (`fallbacks: "default"`), in beta on the Claude API and on [Claude Models on Google Cloud (Anthropic managed)](https://platform.clau… 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… Scale to many tools with tool search Claude Code CLI · in the page agent-sdk/tool-search …yments hosted on Azure. | | `true` | Tool search is on, with the same fallbacks as (unset). | | `auto` | Tool search is off, and tool definitions load upfront, until the definitions it can defer reach… claude-tag Claude Code CLI · in the page claude-tag …bar, tm-stepmeta). These relied on Mintlify theme vars whose light fallbacks rendered as a washed-out gray card on dark backgrounds (reported 6/10). Literal colors below match the dark diagra… Deploy managed settings Claude Code CLI · in the page managed-settings …, or local settings still apply while the managed list is empty. The fallbacks for those two keys and for `allowedChannelPlugins` require Claude Code v2.1.267 or later; earlier versions drop the whol… Connect Claude Code to tools via MCP Claude Code CLI · in the page mcp …yments hosted on Azure | | `true` | MCP tools deferred, with the same fallbacks as (unset) | | `auto` | Threshold mode. Tools that would otherwise be deferred load upfront while their definitions tota… Customize your status line Claude Code CLI · in the page statusline …rst API response completes, so 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… Find bugs with ultrareview Claude Code CLI · in the page ultrareview …t PR, then run `/code-review ultra <PR-number>`. ### 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… Telemetry and egress Claude Documentation · in the page third-party/claude-desktop/telemetry …int` and `otlpProtocol` as the rest of the export, including the gRPC fallbacks described in [Exporter protocol](#exporter-protocol). Span and span-event content is gated by the same `otlpContentCaptu… 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…