LLM model/API behavior drift

Anthropic zero data retention Claude API docs

Identical requests work in one organization and return HTTP 400 in another.

search-observedClaude APIHosted AI APIsLLM model/API behavior driftanthropic_migrate

Agent Quick Fix

SDK types may still accept fields that the selected hosted model rejects; model retirement, tokenizer, thinking, and tool behavior are external and fast-moving.

Product: Claude API
Current-contract area: Zero-data-retention organization cannot use a newer model
Likely root cause: Identical requests work in one organization and return HTTP 400 in another.
Repair direction: Verifier checks current model ID, accepted payload, structured output/tool parsing, and behavior under retries.

Validation Status

Codex searched organically in the validation run. No no-web counterfactual is attached to this page yet.

Symptom

Identical requests work in one organization and return HTTP 400 in another.

Why This Happens

SDK types may still accept fields that the selected hosted model rejects; model retirement, tokenizer, thinking, and tool behavior are external and fast-moving.

Verification

Verifier checks current model ID, accepted payload, structured output/tool parsing, and behavior under retries.

Common Wrong Fixes

Changing local code without checking the current external contract.
Retrying the same install, build, or API call with no version/source change.
Applying a broad unsafe bypass when a narrow compatibility fix is available.

Codex Search Keywords

These are the search terms observed in a neutral Codex validation run for this failure shape.

site:docs.anthropic.com zero data retention Claude API model availability 400 organization
site:docs.anthropic.com data retention zero retention model not supported Anthropic API
Anthropic zero data retention Claude API docs
docs.anthropic.com api errors invalid_request_error model access organization
https://docs.anthropic.com/en/api/errors
https://platform.claude.com/docs/en/about-claude/models/introducing-claude-fable-5-and-claude-mythos-5