Native Anthropic OAuth leaves deferred tool references unrenamed #6531

Client or integration

Claude Code

Area

Provider adapter

Summary

OpenCodex 2.76.0 native Anthropic OAuth renames declared custom tools and tool_use blocks but leaves tool_reference.tool_name unchanged. Resuming a Claude Desktop Code session with deferred MCP tool references returns HTTP 400. Expected references and declarations to use consistent wire names without modifying the conversation or cache markers.

Reproduction

1. Configure an anthropic provider with OAuth to api.anthropic.com.
2. Enable protocols.rollout.managedMessagesNative and managedMessagesNativeOAuth; use one eligible account.
3. Build a Messages request with tool lookup, tool_result.content containing {"type":"tool_reference","tool_name":"lookup"}, and native cache_control markers.
4. The outgoing tool is custom_lookup but the reference is lookup.
5. Anthropic rejects the unmatched reference. A local regression reproduces the wire mismatch without credentials or paid calls.

Version

OpenCodex 2.76.0; Claude Code 2.1.288

Operating system

macOS 27.2

Provider and model

Anthropic OAuth / claude-opus-5-5

Logs or error output

400 Tool reference 'lookup' not found in available tools

The public reproduction uses a synthetic tool name; private session content is omitted.

Screenshots and supporting files

Offline fixture and regression will be linked in the companion PR.

Redacted configuration

{"protocols":{"rollout":{"managedMessagesNative":true,"managedMessagesNativeOAuth":true}}}

Checks

• I searched existing issues and documentation.
• I removed secrets, tokens, account details, request credentials, and personal data.