City time zone and local time

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

Annotations already cover read-only, idempotent and closed-world, and the description adds genuinely non-structured behavior: 7,000+ city coverage, an ambiguity hint ('Springfield' + country), and metered pricing (25 free calls/day, then $0.001 via x402). It says nothing about what happens with ambiguous names or partial matches, which is the main behavioral risk for a name-based lookup.

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?

Three tight sentences, front-loaded with the capability and coverage, then usage trigger, then the cost caveat. Every sentence carries new information and nothing is repeated from the schema or annotations.

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 an output schema exists, the description needn't explain return values, and it does cover scale, input shape, and billing. The gap is ambiguity/error behavior for city names, which matters for a 7,000-city name lookup.

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?

At 50% schema coverage the schema documents 'at' and 'country' but leaves 'city'/'cities' thin; the description compensates with name examples, disambiguation via country, and the 10-item cap. It never explains the 'at' instant parameter or what 'country' filters, so compensation is partial.

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 ('Find the time zone and current local time') plus scope ('up to 10 cities', '7,000+ cities'). It implicitly routes away from siblings by framing itself as the source of the IANA zone 'the other tools need', though it never names the closest alternative (timezone_convert).

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?

Gives concrete triggers — '"what time is it in" questions' and fetching the IANA zone for downstream tools — which is clear usage context. It lacks an explicit when-not statement (e.g. use timezone_convert when you already have a zone and need to convert), so not a 5.

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