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

Annotations already declare readOnlyHint, idempotentHint, closed-world and non-destructive behavior, so safety is fully covered by structured data. The description's '(read-only)' restates the annotation, and the enumeration of returned fields overlaps the output schema, so it adds limited behavioral information beyond what is already given.

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 short sentences with no filler: capability and payload first, the call-first directive last. Every clause carries information an agent needs.

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?

The tool is simple and read-only, an output schema exists so return values need no prose explanation, and the annotations cover the safety profile. Nothing needed to invoke it correctly is missing.

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?

There is only one optional parameter (country) and schema description coverage is 100%, with an example value supplied in the schema. The description mentions the country slug as part of the return payload but adds no filtering syntax or semantics beyond the schema, so the baseline of 3 applies.

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?

States a specific verb and resource ('every city the site covers') plus the payload contents (country/city slugs and hub page URL). The phrase 'the slugs the other tools accept' positions it in the toolset rather than as a search tool, so an agent can separate it from search_places or place without opening a 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?

'Call first when unsure of coverage' gives an explicit trigger condition and ordering advice versus the rest of the toolset. It stops short of naming a specific alternative for when coverage is already known, so it is clear context without full when-not guidance.

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