Discover Codex models and effort levels

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

Goes beyond the readOnly/idempotent annotations by stating 'No inference is run' (no cost or side effects) and warning that 'catalog entries do not guarantee account/provider inference access' — a real interpretation caveat an agent would otherwise get wrong. It stops short of describing catalog size, staleness, or caching behavior.

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?

Three tight sentences with the action directive front-loaded and zero filler. Every sentence carries a distinct fact: what to do, what is returned, and what the result does not imply.

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?

With no output schema, the description compensates by enumerating the returned catalog fields, and it adds the no-inference and access-caveat facts. For a single-optional-parameter read-only tool, nothing an agent needs to call it correctly is missing.

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?

Schema description coverage is 100% and the single optional parameter includeHidden is fully documented in the schema. The description adds nothing about it, so the baseline 3 applies.

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?

States a specific verb and resource ('fetch the current Codex model catalog') and enumerates the payload (descriptions, default model, default effort, supported effort descriptions). Sibling tools are all discussion_* operations, so no differentiation is needed and none is confused.

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?

'Call first' gives an explicit sequencing directive that tells the agent to invoke this before model selection. It lacks an explicit 'do not use when' clause, but there is no competing sibling that would need an exclusion.

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