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

Beyond the readOnly/idempotent/non-destructive annotations, it explicitly states 'Nothing is stored', enumerates the concrete lint checks performed (empty rule set, duplicate/overlapping price items, duplicate forbid ids or phrases, non-cent prices, rules the shipped checker never fires on), and discloses the return fields (valid, errors, warnings). It also adds a substantive caveat that validity implies neither completeness nor execution authority, which the annotations cannot convey.

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?

Front-loaded with the core action, then a dense but purposeful lint list, then two short caveat sentences. Every clause carries information, though the middle enumeration is long enough that it reads as a run-on relative to the compact framing around it.

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 nested-object validation tool with no output schema, the description covers inputs' intent, side effects (none), and the shape of results (valid/errors/warnings), so an agent can call it and interpret the outcome. It does not describe error object structure or how many findings to expect, which is a minor gap given the depth of the nested schema.

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?

With a single required parameter and 100% schema description coverage, the schema already carries the field-level meaning; the description adds value by naming the specific conditions that make a policy invalid (duplicate forbid ids, unrepresentable prices, overlapping price items, dead rules), which are cross-field semantics the schema cannot express.

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 opens with a specific verb and resource ('Check a policy... then lint it') and immediately positions itself relative to the sibling policy_check ('the same schema rules as policy_check, then lint it'), so an agent can tell it apart from the sibling without opening either schema.

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 relationship to policy_check is explicit — this tool validates by the same schema rules and then adds linting — which effectively tells the agent to prefer this one when lint coverage is wanted. It stops short of a stated when-not or a full alternatives list (e.g. fetch, verify_bundle), so it is clear context rather than complete routing guidance.

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