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

Annotations already state readOnlyHint, idempotentHint, and destructiveHint false. The description adds useful behavioral context beyond that: 'Owner-gate exempt — public cohort data only' clarifies permission requirements and data scope. It also explicitly mentions the return format, which helps set expectations. No contradiction with annotations.

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 primary verb and resource, and every clause earns its place. It avoids redundancy and fluff, making it highly scannable and concise.

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?

Given the tool has no output schema, the description takes responsibility for explaining return values ('returns a percentile: "scores better than X% of peers"'). It covers the core inputs (score, country/sector), the dependency on scan_domain, and the permission exemption. The description is fully sufficient for an agent to select and invoke the tool 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?

Schema description coverage is 100%, so baselines are 3. The description does add marginal meaning by linking the score to scan_domain and summarizing country/sector as optional cohort selectors, but it largely restates what the schema already documents. No significant additional parameter semantics provided beyond the schema.

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: 'Rank a domain against its country or global cohort using the GSI benchmark corpus.' It clearly distinguishes the tool's purpose from siblings by emphasizing cohort ranking and the benchmark corpus, and it states the exact output (a percentile). This fully clarifies what the tool does.

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 description provides clear contextual guidance: it references scan_domain as the source of the required score, and explains how country/sector alter the cohort. However, it does not explicitly name alternatives or state when not to use this tool (e.g., vs. get_benchmark). This is a minor omission, so it earns a 4 rather than a 5.

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