gpt-5 is overeager in using claude-code MCP, tool failed, despite getting a result

What version of Codex is running?

0.20.0

Which model were you using?

gpt-5

What platform is your computer?

Darwin 24.5.0 arm64 arm

What steps can reproduce the bug?

Ask any problem that requires analysis on the codebase, such as:
Examine where this environment variable is being used, and how is it being passed around, and are they being used correctly?

Setup mcp server with claude-code

[mcp_servers.claude-code]
command = "claude"
args = ["mcp", "serve"]
env = {}

What is the expected behavior?

It should at least use the claude-code MCP without this tool-failed output, otherwise it should default to using codex's own read, search, and grep either via internal function calls or external tool usage via command line such as ripgrep

What do you see instead?

In most cases, it's using claude-code for most of read, search operations, but why the tool failed? Despite having a result

tool running...
claude-code.Read({"file_path":"/Users/jessearmand/Develop/firecrawl/apps/api/src/lib/parseApi.ts"})

tool failed, duration: 6ms
claude-code.Read({"file_path":"/Users/jessearmand/Develop/firecrawl/apps/api/src/lib/parseApi.ts"})
i: string) {\n  // Handle older versions of the API that don't have the fc- prefix\n  if...
claude-code.Glob({"path":"/Users/jessearmand/Develop/firecrawl/apps/ui/ingestion-ui","pattern":"**/*.{ts,tsx,js,jsx,vue,svelte}"})

tool failed, duration: 76ms
{"filenames": ["/Users/jessearmand/Develop/firecrawl/apps/ui/ingestion-ui/postcss.config.js", "/Users/jessearmand/Develop/firecrawl/apps/ui/ingest
tool running...
claude-code.Read({"file_path":"/Users/jessearmand/Develop/firecrawl/apps/ui/ingestion-ui/src/App.tsx"})

tool failed, duration: 6ms
claude-code.Read({"file_path":"/Users/jessearmand/Develop/firecrawl/apps/ui/ingestion-ui/src/App.tsx"})

{"type": "text", "file": {"filePath": "/Users/jessearmand/Develop/firecrawl/apps/ui/ingestion-ui/src/App.tsx", "content": "import { useState } fro
m \"react\";\nimport FirecrawlComponent from \"./components/ingestion\";\nimport Firecra...

tool running...
claude-code.Grep({"path":"/Users/jessearmand/Develop/firecrawl/apps/ui/ingestion-ui/src","pattern":"Authorization|apiKey|Bearer|VITE_FIRECRAWL_API
","output_mode":"content","n":true,"glob":"**/*.{ts,tsx,js}","head_limit":200})

tool failed, duration: 801ms
claude-code.Grep({"path":"/Users/jessearmand/Develop/firecrawl/apps/ui/ingestion-ui/src","pattern":"Authorization|apiKey|Bearer|VITE_FIRECRAWL_API
{"mode": "content", "numFiles": 0, "filenames": [], "content": "/Users/jessearmand/Develop/firecrawl/apps/ui/ingestion-ui/src/lib/config.ts:  apiK
tool running...
claude-code.Read({"file_path":"/Users/jessearmand/Develop/firecrawl/apps/ui/ingestion-ui/src/lib/config.ts"})

tool failed, duration: 4ms
claude-code.Read({"file_path":"/Users/jessearmand/Develop/firecrawl/apps/ui/ingestion-ui/src/lib/config.ts"})

{"type": "text", "file": {"filePath": "/Users/jessearmand/Develop/firecrawl/apps/ui/ingestion-ui/src/lib/config.ts", "content": "/**\n * Configura
tion management for Firecrawl UI\n * Handles environment variables and provides validati...