codex_models

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The description details behavioral traits beyond annotations: reads from cache or fallback with source indication, no model call, stability warning ('not fingerprint-stable'), and validation delegation. No contradiction with readOnlyHint and openWorldHint annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is well-structured and front-loaded with purpose, but slightly verbose with multiple caveats. However, every sentence adds value, so it balances completeness with conciseness.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given no parameters, existing output schema, and clear annotations, the description is comprehensive. It covers purpose, internal behavior, limitations, and advisory nature, leaving no gaps for the agent.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

No parameters exist, baseline is 4 per rule. The description does not need to add parameter information, and it adds no additional semantics beyond the schema, but this is appropriate given zero parameters.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states it lists Codex model slugs with their reasoning effort, using specific verbs and resource identification. It distinguishes from siblings by being advisory, free, and about model slugs, fulfilling the best practice for purpose clarity.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description explicitly says 'Advisory discovery only' and warns against using cached data, noting that unlisted values may work and listed ones may be unavailable. It also mentions it is the same payload as codex://models, providing clear when-to-use and when-not-to guidance.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.