List Codex models

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

readOnlyHint=true already declares the safety profile, so the bar is lower. The description still adds real context: the data comes from both the user's account and the configured default in config.toml, and it names what each entry contains. It omits anything about ordering or result size, but for a small enumeration that is minor.

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?

Two sentences, both earning their place: the first defines the output, the second gives the call trigger. No redundancy and no filler.

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 present, the description carries the return-value burden and does so by listing the fields returned and where the default comes from. Combined with the explicit usage trigger, an agent has everything needed to invoke it correctly.

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?

Only one parameter and schema description coverage is 100%, so the schema fully documents include_hidden. The description says nothing about it, adding no meaning beyond structured data, which is the baseline-3 case.

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?

Specific verb (List) + resource (Codex models) scoped to the user's account, and it enumerates the returned fields (slug, description, reasoning efforts, default effort) plus the config.toml default. Siblings (codex_job, codex_task, codex_image, codex_jobs) are plainly different resources, so no confusion arises.

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?

Explicitly states when to call it: 'Use before choosing `model` / `reasoning_effort`.' That gives a clear triggering condition. It does not name an alternative tool or an exclusion case, so it stops short of a 5.

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