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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and a closed world, so the safety profile is fully covered structurally. The description adds the cost trait ('Free') and the freshness indicator (last update time), which are genuinely beyond the annotations, but says nothing about how the 'today' coverage snapshot is scoped or refreshed.

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?

A single short sentence with the most decision-relevant token ('Free') front-loaded, followed by the payload contents. No filler, no repetition of the tool name or title.

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 zero-parameter, closed-world informational tool with a full output schema and complete annotations, the definition is essentially sufficient; return values needn't be explained in prose since the output schema carries them. The only minor gap is the absence of any hint about cache/refresh cadence behind 'last update time'.

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?

The tool takes zero parameters, so the baseline is 4 per the rubric. There is nothing for the schema to document and nothing for the description to compensate for; no parameter claims are made or needed.

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 the resource (coverage) and enumerates the concrete payload — covered cities, permit counts, date range, last update time — which distinguishes it from the data-returning siblings like search_permits and get_permit. The verb is only implicit ('reports'), but the scope is unambiguous enough for an agent to distinguish an informational metadata tool.

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 leading 'Free.' is a mild usage signal (call this at no cost, unlike possibly metered siblings), but there is no explicit when-to-use statement, no mention of checking coverage before running searches, and no named alternative. Usage is only implied.

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