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

Annotations already state readOnlyHint=true and idempotentHint=true, so no safety ambiguity exists. The description adds valuable behavioral detail beyond that: counts are exact-match coverage counts, state hubs require at least 25 listings, data hubs are file-backed and need no database, and the coverage counts do not guarantee search engine indexing.

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?

The description is front-loaded with the core purpose and then uses a compact semicolon-delimited list to cover all four kind variants without redundancy. The closing caveat about coverage counts vs. search-engine indexing is meaningful and prevents misuse rather than padding.

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 tool with no output schema, the description gives enough context to call it correctly: all kind values, their URL shapes, count meanings, and the file-backed data behavior. Combined with the annotations carrying the read-only/idempotent safety profile, an agent has what it needs to select and invoke the tool appropriately.

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 schema description coverage at 0%, the description compensates strongly by defining every kind enum value with concrete URL templates and selection criteria. However, the limit parameter is never mentioned in the description, so the compensation is partial even though the schema already documents its default and bounds.

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 exactly what the tool provides: public hub list pages with coverage counts, broken into kind-specific URL patterns. The detail for each kind—category, city, state, data—makes the tool's purpose concrete and distinguishes it from the other ranked_* siblings that serve business checks or rankings queries.

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 gives clear selection context for each kind value, telling the agent which URL form and inclusion criteria apply. It does not explicitly name alternative tools or say when not to use ranked_hubs, so it stops short of full sibling routing guidance.

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