Implement Automatic Model Fallbacks to Maintain Workflow Continuity
Prevent automated workflow breaks by configuring model fallbacks for refusals.
Use the new 'fallbacks' API parameter to automatically reroute requests to a secondary model if Claude Fable 5 issues a 'refusal' stop reason.
The Scenario
You are building an automated agent that processes user-generated content and you want to ensure the workflow doesn't stop if a specific model's safety classifier triggers a refusal.
Before & after
When a model refused a request due to safety filters, you had to manually rewrite the prompt or switch models yourself, which could take 5-10 minutes per occurrence.
By enabling the 'fallbacks' parameter in your API calls, the system automatically redirects to an alternative model in seconds without manual intervention.
The Prompt
// API Configuration Example
{
"model": "claude-fable-5",
"max_tokens": 4096,
"fallbacks": ["claude-sonnet-4.6"],
"messages": [{"role": "user", "content": "[YOUR_COMPLEX_PROMPT]"}]
}The new opt-in fallbacks parameter is ideal for agentic workflows where you don't want a refusal to break the entire chain of operations.
Source
Claude Platform - Claude API Docs"An opt-in fallbacks parameter... re-runs refused requests on another model, billed at the fallback model's rates."