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

Annotations already declare readOnly, idempotent and non-destructive, so the safety profile is covered. The description adds only the ambiguity-trigger context and nothing about return format or rate limits, which the output schema partly handles anyway.

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 waste; the positive use case is front-loaded and the exclusion follows. It earns its length, though the opening phrase is fuzzier than it needs to be.

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 single-parameter read-only discovery tool with an output schema and covering annotations, the description is roughly adequate. However, 'coverage' and 'supported exact place/area keys' are left ambiguous, so an agent still has to guess what it actually gets back.

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 description coverage is 0% and the single 'locale' parameter is never mentioned in the description. The enum values (en/es) are somewhat self-explanatory, but the description does nothing to compensate for the missing schema documentation.

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 conveys that this returns filter/coverage data and supported place/area keys, but 'Discover current coverage' is vague about what is actually being covered or returned. A specific verb+resource is only loosely present, so an agent gets the gist but not a crisp statement of purpose.

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?

It gives an explicit trigger ('when the destination is ambiguous') and an explicit when-not ('Not needed for searches with city, region or country text'). It stops short of naming an alternative sibling tool to use instead, but the selection condition is clear.

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