Coordinates to address

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

With no annotations, the description carries the full burden. It discloses the null-and-reason behavior for ocean/unmapped points, the OpenStreetMap Nominatim data source, and the cost/payment mechanism, which are important runtime behaviors.

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?

The description is three sentences, front-loaded with the core purpose, followed by behavioral and cost information. No filler or repetition of schema 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?

The tool is simple with 2 params, but there is no output schema, so the description should explain the return value more fully. It mentions 'structured components' but doesn't enumerate them, and it doesn't mention potential errors aside from the null case. Still, cost and data source add context beyond the minimum.

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 100%, with both lat and lon already described. The description adds no parameter-specific details 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?

The description clearly states 'turn latitude/longitude into a street address with structured components', using a specific verb and resource. By calling it 'Reverse geocoding', it distinguishes itself from the sibling 'geocode' tool.

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 explicitly frames the tool as reverse geocoding, indicating its use case, but does not name alternatives or state when not to use it. The sibling tool 'geocode' implies the forward direction, but no explicit exclusion is provided.

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