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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safe-external-read profile is covered. The description adds some value by naming the upstream data source (Nominatim JSONv2) and the default behaviors of addressdetails/extratags, but omits operational traits like rate limits that Nominatim is known for. Adequate but not rich.

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?

Short, front-loaded sentences with the purpose first and the reverse-geocoding pointer last. Slightly fragmented and partly redundant with the schema (repeating addressdetails/extratags defaults), which keeps it out of the top band.

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 100% schema coverage, an output schema, and annotations present, the definition needs only to orient the agent, which it does well: purpose, input-mode constraint, and reverse alternative. Missing rate-limit and result-volume context is minor given the structured metadata.

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 100%, so the schema already documents all 13 parameters including defaults for addressdetails and extratags. The description's restatement of those two defaults adds little beyond the schema, so the baseline 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 ('Returns typed Nominatim JSONv2 forward geocoding results'), naming the exact operation and data format. It clearly distinguishes forward geocoding from the reverse-geocoding sibling, so an agent can tell it apart 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?

Explicitly states the input constraint ('Use either q or structured fields, not both') and routes the agent to geocoding_reverse for reverse lookups. It does not mention the other sibling (geocoding_lookup) or when to prefer one, so a minor routing gap remains.

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