list_supported_cities

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

With no annotations provided, the description carries the full behavioral disclosure burden. It clearly states this is a read-only operation returning a JSON list of a fixed set of 22 cities with specific fields, and there are no side effects implied. It does not mention edge cases or errors, but for a zero-argument listing operation this is a minor gap.

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, zero filler: the first states the output shape and cardinality, the second gives the critical usage cue. The most important information is front-loaded and every sentence adds value.

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 discovery tool with an output schema, the description is complete: it states the output format, cardinality, fields, and the intended first-call usage. Nothing an agent needs 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?

The tool has zero parameters and a 100% schema coverage, so parameter documentation is trivially complete. Per the baseline for zero-parameter tools, a score of 4 is appropriate; the description's mention of discovering valid city names also indirectly explains how the output will be used as input to sibling tools.

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: it 'Returns a JSON list of 22 pre-configured cities' and enumerates the contained fields. This clearly distinguishes it from the sibling astrological-calculation tools, and 'Call this first to discover valid city names' reinforces its role as a discovery endpoint.

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 instruction 'Call this first to discover valid city names' provides explicit sequencing guidance, telling an agent when to invoke this tool relative to other city-dependent calls. It does not explicitly discuss alternatives or when not to use it, but that is less relevant for a zero-argument discovery tool among calculation siblings.

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