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Invalid schema for function - Codex error

Quick fix

Upgrade cc-switch for the tool schema conversion fix. If upstream rejects oneOf strictly, use a historical task or switch model for now.

Symptom

Section titled “Symptom”
Error output
Invalid schema for function 'codex_app__automation_update': schema must be a JSON Schema of 'type: "object"', got 'type: null'.

Cause

Section titled “Cause”

The JSON Schema of built-in desktop tools injected by Codex and Claude Code (codex_app__automation_update, for example) is missing `"type": "object"` at the root level, or uses oneOf. When cc-switch converts the Responses format into OpenAI Chat Completions and forwards it to a third-party provider such as DeepSeek or Databricks, the upstream API validates the JSON Schema strictly and returns HTTP 400.

Early cc-switch versions did not handle the type: null case. Later versions (after PR #4706 landed) normalise it to {"type": "object", "properties": {}}, but still keep a top-level oneOf when handling a complex schema — so upstreams that validate extremely strictly, such as OpenAI models hosted on Databricks, still reject the request.

Fix

Section titled “Fix”

  1. Upgrade cc-switch to the latest version (at minimum one containing PR #4706) to fix the 400 from type: null on upstreams such as DeepSeek.

  2. On an upstream that strictly rejects a top-level oneOf, such as Databricks, keep using a historical task for now (the deferred namespace mechanism avoids exposing that tool directly), or switch to a model provider that validates schemas less strictly.

Affected Versions

Section titled “Affected Versions”
ToolCodex / Claude Code
Version3.14.3 - 3.19.1
PlatformsWindowsmacOS

Source Issues

Section titled “Source Issues”

This page is distilled from 4 real issues

FAQ

Section titled “FAQ”
Why does connecting to the official API directly work while going through the cc-switch proxy errors?
The official API validates tool schemas loosely, while cc-switch converts the request into OpenAI Chat Completions and forwards it to a third party such as DeepSeek, which validates the JSON Schema strictly.
It still reports a oneOf error after upgrading cc-switch. What now?
Some upstreams such as Databricks reject a schema containing a top-level oneOf. Until cc-switch flattens the schema fully, try using a historical task to trigger the deferred namespace mechanism, or switch to an upstream model that validates less strictly.
Section titled “Related problems”
Ticking 1M for DeepSeek does nothing? cc-switch local proxy configWith the cc-switch local proxy on, do not enter [1m] and leave the main model empty. The [1m] suffix only works with the proxy off.4 issues mergedapi failed deserialize json body intoDepending on the error: roll Claude Code back, upgrade cc-switch, turn the local proxy off, or stop sending unsupported fields.7 issues mergedCC Switch local proxy failed while handlingUpgrade CC Switch to the latest version and start a new Codex conversation; invalid schema or image blocks left in old session history will keep triggering 400.43 issues merged

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