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

Beyond the annotations, the description adds a per-call cost ($0.01), the data source and its implications, the shape of the return payload (display names, country/region/type, retrieval time, attribution), and precision caveats. That is substantial disclosure for a read-only, idempotent lookup with no output schema.

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 sentences, front-loaded with the core action, followed by return contents and then limits and cost. Every sentence carries distinct information and nothing is repeated from structured fields.

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 lookup with no output schema, the description supplies what the schema cannot: pricing, data source, return contents, attribution, and accuracy limits. An agent has everything needed to decide to call it and to interpret the result.

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?

With one parameter at 100% schema description coverage, the schema already defines 'address' fully. The description's phrasing ('street address, place name or landmark') echoes the schema's own description rather than adding new constraint or format guidance, so 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?

The description opens with a specific verb and resource ('Resolve a street address, place name or landmark to ranked coordinates') and names the underlying provider (OpenStreetMap Nominatim). No sibling tool performs geocoding, so the absence of explicit sibling routing is not a defect.

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 makes clear when to use it (resolving addresses, place names, or landmarks) and states fitness exclusions: results are not legal boundaries, navigation routes, or survey-grade coordinates. There is no named alternative to route to, which caps this below a 5.

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