on-failure
Only ask when operations fail
How to use it
on-failure is exposed by the Codex MCP Server MCP server. Add the server to your MCP client (Claude Desktop, Cursor, Windsurf and others), and the on-failure tool becomes available to the model automatically. See the full listing for setup details and every tool this server provides.
Install Codex MCP Server
claude mcp add codex-cli -- npx -y @cexll/codex-mcp-serverOther tools in Codex MCP Server (18)
Controls when user approval is required
(o3-based for software engineering)
(low-latency code Q&A)
Full system access including network
Shorthand for sandboxMode: "workspace-write" + approvalPolicy: "on-failure"
(also available)
(general purpose, fast reasoning)
(default, optimized for coding)
~/Library/Application Support/Claude/claudedesktopconfig.json
No approvals required
(smartest, deep reasoning)
(fast & efficient)
Ask before every action
Analysis only, no file modifications
Controls file system access level
Maximum paranoia mode
Can modify files in workspace
⚠️ Bypasses all safety checks (dangerous, not recommended)