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

Annotations already declare it read-only, idempotent, non-destructive and closed-world; the description still adds real value: nothing is stored, the return payload is valid/errors/warnings, the never-fired-rule detection is done by probing with the shipped checker, and validity is explicitly distinguished from completeness and from execution authority. That is substantive behavioral context beyond the structured fields.

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?

Roughly three dense sentences, front-loaded with the verb and the policy_check relationship, then the lint catalogue, then the return values and the safety caveat. No filler and no repetition of annotation content.

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 validation tool with no output schema, the description does supply the return shape and the meaning of a pass, which is the main gap it needed to cover. However, with an opaque nested policy object at 0% schema coverage, an agent still cannot tell what a well-formed input looks like, which is a clear remaining gap for this complexity.

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?

There is a single required parameter, but schema coverage is 0% and the parameter is a free-form nested object with no described structure, so the 1-param baseline does not apply. The description describes the checks performed but never says what a policy object contains, leaving the agent with no guidance on constructing the input.

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 pair (check + lint) on a specific resource (a policy) and explicitly relates itself to the sibling policy_check, which it extends rather than duplicates. The enumerated lint categories (empty rules, duplicate price items, duplicate forbid ids/phrases, uncentsable prices, never-firing rules) make the scope unmistakable.

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?

By stating it performs the policy_check schema rules and then lints, it implies choosing this over policy_check when lint feedback is wanted, and it clarifies that a valid result does not mean a complete policy or grant execution authority. It stops short of an explicit 'use this instead of policy_check when...' or any exclusion, so it is clear context rather than full routing guidance.

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