Anthropic API / Anthropic API

Xiaomi MiMo Token Plan Anthropic-Compatible Endpoint: 400 Error with Thinking and Tool Use Replay

Fix 400 error when using Xiaomi MiMo Token Plan Anthropic-compatible endpoint with thinking mode and tool_use message replay Includes evidence for Anthropic API troubleshooting demand.

Source-backed Last updated May 13, 2026 1 source Needs local verification

Category: Anthropic API
Error signature: MiMo Token Plan Anthropic-compatible endpoint returns 400 when thinking + tool_use history is replayed
Quick fix: Compare the failing environment with a known working setup, then change one configuration value at a time.
Updated: May 13, 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 Anthropic API, 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

MiMo Token Plan Anthropic-compatible endpoint returns 400 when thinking + tool_use history is replayed is a Anthropic API failure pattern reported for developers trying to fix 400 error when using xiaomi mimo token plan anthropic-compatible endpoint with thinking mode and tool_use message replay. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

Reproducible on macOS Apple Silicon with Craft Agents 0.9.2. MiMo Token Plan is a paid Xiaomi AI service. The endpoint at token-plan-cn.xiaomimimo.com/anthropic implements a subset of Anthropic Messages API. Thinking + tool_use replay triggers 400.

Common causes

Developers using Xiaomi MiMo Token Plan's Anthropic-compatible API endpoint encounter 400 errors when the conversation history contains both thinking blocks and tool_use messages. The endpoint implements a subset of the Anthropic Messages API but fails to handle the thinking + tool_use combination correctly, breaking multi-turn agentic workflows.
Reproducible on macOS Apple Silicon with Craft Agents 0.9.2. MiMo Token Plan is a paid Xiaomi AI service. The endpoint at token-plan-cn.xiaomimimo.com/anthropic implements a subset of Anthropic Messages API. Thinking + tool_use replay triggers 400.

Quick fixes

Confirm the exact error signature matches MiMo Token Plan Anthropic-compatible endpoint returns 400 when thinking + tool_use history is replayed.
Check the Anthropic API account, local tool state, and provider configuration involved in the failing workflow.
Compare the failing environment with a known working setup, then change one configuration value at a time.

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 MiMo Token Plan Anthropic-compatible endpoint returns 400 when thinking + tool_use history is replayed exactly before applying the quick fix.
Compare the failing environment with Anthropic API 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 MiMo Token Plan Anthropic-compatible endpoint returns 400 when thinking + tool_use history is replayed mean in Anthropic API?

MiMo Token Plan Anthropic-compatible endpoint returns 400 when thinking + tool_use history is replayed indicates the workflow described by "Xiaomi MiMo Token Plan Anthropic-Compatible Endpoint: 400 Error with Thinking and Tool Use Replay" failed in a Anthropic API context. Start by confirming the exact signature and the component that emitted it.

What should I check first for MiMo Token Plan Anthropic-compatible endpoint returns 400 when thinking + tool_use history is replayed?

Check whether this cause matches your environment: Developers using Xiaomi MiMo Token Plan's Anthropic-compatible API endpoint encounter 400 errors when the conversation history contains both thinking blocks and tool_use messages. The endpoint implements a subset of the Anthropic Messages API but fails to handle the thinking + tool_use combination correctly, breaking multi-turn agentic workflows.

Is the MiMo Token Plan Anthropic-compatible endpoint returns 400 when thinking + tool_use history is replayed guidance source-backed?

The "Xiaomi MiMo Token Plan Anthropic-Compatible Endpoint: 400 Error with Thinking and Tool Use Replay" 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 MiMo Token Plan Anthropic-compatible endpoint returns 400 when thinking + tool_use history is replayed?

For "Xiaomi MiMo Token Plan Anthropic-Compatible Endpoint: 400 Error with Thinking and Tool Use Replay", avoid applying "Compare the failing environment with a known working setup, then change one configuration value at a time." 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 MiMo Token Plan Anthropic-compatible endpoint returns 400 when thinking + tool_use history is replayed?

For "Xiaomi MiMo Token Plan Anthropic-Compatible Endpoint: 400 Error with Thinking and Tool Use Replay", collect the failing Anthropic API command or request, non-secret configuration, versions, timestamps, request IDs when available, and the smallest reproduction that still triggers the signature.