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Invalid schema: got 'type: null' - Claude Code

Quick fix

Upgrade cc-switch to v3.17.0 or later to fix the missing type field error during OpenAI format conversion.

Symptom

Section titled “Symptom”
Error output
API Error: 400 Error from provider (DeepSeek): Invalid schema for function 'web_search': schema must be a JSON Schema of 'type: "object"', got 'type: null'.

Cause

Section titled “Cause”

When using cc-switch to connect Claude Code to an OpenAI Chat Completions API such as OpenCode Go, if the client sends Anthropic-format tool calls (such as web_search, Bash, or Write) that omit the top-level type field, the cc-switch conversion layer (clean_schema in transform.rs) passes the schema through unchanged. The resulting OpenAI-format parameters object then lacks a type field (type: null). Strict API gateways such as DeepSeek reject this format and return a 400 error. This was fixed in v3.17.0; the conversion layer now defaults a missing root-level type to "object".

Fix

Section titled “Fix”

  1. Upgrade cc-switch to v3.17.0 or later. This version fixes the schema defect during Anthropic-to-OpenAI format conversion.

  2. As a temporary workaround, bypass the OpenCode Go OpenAI-compatible interface and configure the DeepSeek native Anthropic-compatible API directly in cc-switch (for example, set the base URL to https://api.deepseek.com/anthropic).

Affected Versions

Section titled “Affected Versions”
ToolClaude Code
Version3.16.0 - 3.16.1
PlatformsmacOSWindows

Source Issues

Section titled “Source Issues”

This page is distilled from 2 real issues

FAQ

Section titled “FAQ”
Why do only some tools (such as WebSearch and Agent) fail while TaskList works?
Parameterless tools such as TaskList do not need a complex JSON Schema. Parameterized tools such as WebSearch, Bash, and Write had their parameter object type field incorrectly set to null during Anthropic-to-OpenAI conversion, causing validation failures on strict backends.
Are MCP tools affected by this issue?
No. MCP tools use a separate protocol channel and do not pass through Anthropic-to-OpenAI format conversion, so they are not affected by this schema corruption issue.
Section titled “Related problems”
Volcengine Agent Plan Auto-Identify Model List Failed 404Manually modify config.toml to match official docs and add models in modelCatalog to bypass 404.2 issues mergedcontent[].thinking must be passed backUpgrade cc-switch to v3.16.0 or newer. As a stopgap, roll Claude Code back to 2.1.150 or turn thinking off.11 issues merged"is not a model this version of Claude Code recognizes" - CC SwitchSet CLAUDE_CODE_MAX_CONTEXT_TOKENS or append [1m] to the model name to define the correct context window size.3 issues merged

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