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

Annotations already declare the safety profile (readOnly, idempotent, non-destructive), so the bar is lower. The description adds genuinely new semantics: the returned areas 'are public locality centers, never property coordinates', which tells the agent what the data actually represents and prevents misuse as coordinates.

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 purpose, then the usage mechanic, then the semantic caveat and fallback. No filler and every clause carries information.

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?

With an output schema present, the description needn't explain return values, and annotations cover safety. It covers purpose, routing to alternatives, and the nature of the returned data; the only gap is the undocumented locale parameter.

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?

Schema coverage is 50% – the q parameter is fully documented in the schema while locale has no description anywhere. The description reinforces q's semantics (town, region or country search) and the empty-list behavior, but adds nothing about locale, so it fails to compensate for the coverage gap.

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 named public areas with published chucho homes') and distinguishes itself from siblings: it handles unmapped homes via search_properties and feeds 'nearby search' via the returned area key. An agent can tell it apart from search_properties and search_nearby_properties without opening the 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?

Gives clear context ('Search a destination's town, region or country') and names the alternative with its selecting condition ('unmapped homes remain searchable with search_properties'). It also says to reuse the returned area key for nearby search. No explicit when-not-to-use beyond those conditions, so not quite a 5.

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