LiteLLM / LiteLLM

LiteLLM Proxy Returns Incorrect Tool Choice Error for Anthropic Adaptive-Thinking Models

Fix LiteLLM proxy errors when calling Anthropic adaptive-thinking models, where LiteLLM incorrectly forces tool_choice parameter and causes API requests to be rejected by Anthropic. Includes evidence for LiteLLM troubleshooting demand.

Source-backed Last updated May 17, 2026 1 source Needs local verification

Category: LiteLLM
Error signature: LiteLLM forces tool_choice parameter on adaptive-thinking Anthropic models (Claude Opus 4.7 etc.) causing request rejection — fix applied in pull #28114
Quick fix: Verify the model name, local service connectivity, and network access before retrying the model pull.
Updated: May 17, 2026
Verification status: Source-backed
Evidence: 1 public source URL

Before you change production

This page includes public source URLs in the imported troubleshooting record. Compare those references with your version and environment before applying changes.

Reproduce the smallest failing action and save non-secret logs before changing configuration.
Check versions for LiteLLM, related SDKs, package managers, CI runners, and hosting providers.
Change one setting or dependency at a time, then rerun the same failing command or request.
Avoid destructive commands, credential rotation, billing changes, or security relaxations without a rollback plan.

What this error means

LiteLLM forces tool_choice parameter on adaptive-thinking Anthropic models (Claude Opus 4.7 etc.) causing request rejection — fix applied in pull #28114 is a LiteLLM failure pattern reported for developers trying to fix litellm proxy errors when calling anthropic adaptive-thinking models, where litellm incorrectly forces tool_choice parameter and causes api requests to be rejected by anthropic.. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

Source: BerriAI/litellm#28114 (updated 2026-05-17). Live PR fixing LiteLLM forcing unsupported tool_choice on adaptive-thinking Anthropic models. Directly impacts paid LiteLLM proxy users — every affected request wastes tokens. This was recently fixed but developers encountering it before the fix need troubleshooting guidance. Category: LiteLLM per exact mapping.

Common causes

Source: BerriAI/litellm#28114 (updated 2026-05-17). Live PR fixing LiteLLM forcing unsupported tool_choice on adaptive-thinking Anthropic models. Directly impacts paid LiteLLM proxy users — every affected request wastes tokens. This was recently fixed but developers encountering it before the fix need troubleshooting guidance. Category: LiteLLM per exact mapping.

Quick fixes

Confirm the exact error signature matches LiteLLM forces tool_choice parameter on adaptive-thinking Anthropic models (Claude Opus 4.7 etc.) causing request rejection — fix applied in pull #28114.
Check the LiteLLM account, local tool state, and provider configuration involved in the failing workflow.
Verify the model name, local service connectivity, and network access before retrying the model pull.

Platform/tool-specific checks

Verify the command, editor, extension, or API client that produced the error.
Compare local settings with CI, deployment, or editor-level settings when the error appears in only one environment.
Avoid deleting credentials, local model data, or project settings until the failing scope is clear.

Step-by-step troubleshooting

Capture the exact error message and the command, editor action, or request that triggered it.
Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
Review the source evidence below and compare it with your environment.
Apply one change at a time and rerun the smallest failing action.
Keep the working fix documented for the team or deployment environment.

How to prevent it

Keep provider/tool configuration documented.
Record non-secret diagnostics such as tool version, provider name, model name, and command path.
Add a lightweight check before CI or production workflows depend on the tool.

Diagnostic flow for this page

Match LiteLLM forces tool_choice parameter on adaptive-thinking Anthropic models (Claude Opus 4.7 etc.) causing request rejection — fix applied in pull #28114 exactly before applying the quick fix.
Compare the failing environment with LiteLLM versions, account scope, provider settings, and deployment context.
Check the listed common causes in order, starting with the cause that best matches your logs.
Use the evidence status below to decide whether to confirm against public sources or official documentation.
Apply one reversible change, rerun the smallest failing action, and keep rollback notes.

FAQ

What does LiteLLM forces tool_choice parameter on adaptive-thinking Anthropic models (Claude Opus 4.7 etc.) causing request rejection — fix applied in pull #28114 mean in LiteLLM?

LiteLLM forces tool_choice parameter on adaptive-thinking Anthropic models (Claude Opus 4.7 etc.) causing request rejection — fix applied in pull #28114 indicates the workflow described by "LiteLLM Proxy Returns Incorrect Tool Choice Error for Anthropic Adaptive-Thinking Models" failed in a LiteLLM context. Start by confirming the exact signature and the component that emitted it.

What should I check first for LiteLLM forces tool_choice parameter on adaptive-thinking Anthropic models (Claude Opus 4.7 etc.) causing request rejection — fix applied in pull #28114?

Check whether this cause matches your environment: Source: BerriAI/litellm#28114 (updated 2026-05-17). Live PR fixing LiteLLM forcing unsupported tool_choice on adaptive-thinking Anthropic models. Directly impacts paid LiteLLM proxy users — every affected request wastes tokens. This was recently fixed but developers encountering it before the fix need troubleshooting guidance. Category: LiteLLM per exact mapping.

Is the LiteLLM forces tool_choice parameter on adaptive-thinking Anthropic models (Claude Opus 4.7 etc.) causing request rejection — fix applied in pull #28114 guidance source-backed?

The "LiteLLM Proxy Returns Incorrect Tool Choice Error for Anthropic Adaptive-Thinking Models" page is labeled source-backed. It has 1 public source URL from github.com, so use that evidence status when deciding how much additional verification you need.

When should I avoid the quick fix for LiteLLM forces tool_choice parameter on adaptive-thinking Anthropic models (Claude Opus 4.7 etc.) causing request rejection — fix applied in pull #28114?

For "LiteLLM Proxy Returns Incorrect Tool Choice Error for Anthropic Adaptive-Thinking Models", avoid applying "Verify the model name, local service connectivity, and network access before retrying the model pull." when the error text differs, the affected version or provider is different, or the change would touch credentials, billing, DNS, production deploy settings, or irreversible data.

What should I collect before debugging LiteLLM forces tool_choice parameter on adaptive-thinking Anthropic models (Claude Opus 4.7 etc.) causing request rejection — fix applied in pull #28114?

For "LiteLLM Proxy Returns Incorrect Tool Choice Error for Anthropic Adaptive-Thinking Models", collect the failing LiteLLM command or request, non-secret configuration, versions, timestamps, request IDs when available, and the smallest reproduction that still triggers the signature.