Check the Codex CLI installation

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

The annotations already declare readOnlyHint=true and openWorldHint=false, and the description's 'never installs or changes anything' reinforces that safety profile without contradicting it. It adds useful behavioral scope by explaining the inspection covers signed-in state and configuration loading, and that it emits remediation steps rather than performing fixes. It doesn't detail the exact return format or mention the cached diagnosis behavior described in the refresh parameter, but the schema covers that.

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 sentences, no fluff, and the most decision-relevant facts come first: what it checks, when to run it, and what it will not do. Every sentence earns its place, and the coverage of purpose, usage, and safety is achieved in extremely compact form.

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?

For a zero-required-parameter diagnostic tool, the definition is complete: it states the checks performed, what the output will contain (fix steps), when to invoke it, and that it is read-only. The schema covers the two optional parameters, and the annotations cover the side-effect profile, so nothing needed for correct selection or invocation 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 both parameters already have strong descriptions: refresh explains the cache/re-probe behavior)Skip and working_dir explains the directory-sensitive configuration loading and its default. The tool description contributes contextual motivation by tying the check to delegation, but it does not add meaning beyond what the schema already provides. A baseline 3 is appropriate because the schema carries the parameter documentation burden.

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 names a specific verb ('check') and a concrete resource (the local Codex CLI installation), then elaborates with four concrete checks: installed, recent enough, signed in, and able to load configuration. It also states the actual outcome ('report the exact steps to fix it'), which differentiates this diagnostic tool from the delegation, recommendation, and job-management siblings.

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?

It gives explicit trigger conditions: run when another tool reports the CLI is unavailable, or before relying on delegation for the first time. It also states a clear exclusion—it only inspects and never installs or changes anything—so an agent knows not to use it as a fixer and should look elsewhere for remediation.

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