Bug type

Behavior bug (incorrect output/state without crash)

Beta release blocker

No

Summary

On OpenClaw 2026.4.2 with model openai/gpt-5.4, flux-operator-mcp is rejected with HTTP 400: Invalid schema for function 'flux-mcp__get_flux_instance': In context=(), object schema missing properties.

Steps to reproduce

1. Run OpenClaw 2026.4.2 with model openai/gpt-5.4.
2. Configure flux-operator-mcp.
3. Trigger a request path that registers or uses flux-mcp__get_flux_instance.
4. Observe the request fail with HTTP 400: Invalid schema for function 'flux-mcp__get_flux_instance': In context=(), object schema missing properties.

Expected behavior

The MCP tool schema should be accepted on the OpenAI Responses path. Issue #58246 was closed by #58299, and the release notes state that raw bundled MCP tool schemas were normalized so bare-object MCP tools would no longer be rejected during OpenAI tool registration.

Actual behavior

The request fails on OpenClaw 2026.4.2 with model openai/gpt-5.4, returning HTTP 400: Invalid schema for function 'flux-mcp__get_flux_instance': In context=(), object schema missing properties.

OpenClaw version

2026.4.2

Operating system

node:24-bookworm (default)

Install method

Official OpenClaw image

Model

openai/gpt-5.4

Provider / routing chain

openclaw -> openai

Additional provider/model setup details

No response

Logs, screenshots, and evidence

2026-04-03T07:35:49.377+00:00 [agent/embedded] embedded run agent end: runId=3973d6c6-4f3c-421e-9f6b-26d4d262b222 isError=true model=gpt-5.4 provider=openai error=HTTP 400: Invalid schema for function 'flux-mcp__get_flux_instance': In context=(), object schema missing properties. rawError=400 Invalid schema for function 'flux-mcp__get_flux_instance': In context=(), object schema missing properties.

Impact and severity

Affected: OpenClaw 2026.4.2 deployments using model openai/gpt-5.4 with flux-operator-mcp and similar MCP servers exposing parameter-free tool schemas
Severity: High (blocks agent operation with the affected MCP servers)

Additional information

This appears similar to #58246, but the observed reproduction is on openai/gpt-5.4 rather than openai-codex/gpt-5.4.