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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description goes beyond them by disclosing the shape of the analysis — section-level coverage, per-rule reach, and unmatched rules — which tells the agent what kind of answer to expect. It stops short of stating cost, limits, or whether it runs against a stored estate or the passed document.

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, front-loaded with the core verb and resource, no filler. The trailing analogy is compact and clarifying rather than redundant, though it costs a little precision compared to simply naming the input domain.

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 read-only analytic tool with no output schema, fully documented parameters, and clear annotations, the description supplies enough: what is measured and at what granularity. What an agent might still want — the exact report structure or whether it requires a previously stored estate — is not addressed.

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 (document, context) are fully documented in the schema, so the baseline is 3. The description adds no format or constraint detail about the document parameter beyond what the schema states.

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 states a specific verb and resource: 'Measure how much of an API description your governance actually inspects', with three concrete output facets (coverage by section, each rule's reach, rules matching nothing). It is clearly distinguishable from data-retrieval siblings, but it never names or contrasts with the closest analytic siblings like api_scorecard, audit_pipeline, or governance_report, leaving the boundary slightly implicit.

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 'Like test coverage, one altitude up' analogy hints at the mental model but gives no explicit when-to-use condition, no prerequisites, and no guidance on choosing this over api_scorecard or governance_report. An agent must infer applicability from the purpose statement alone.

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