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

No annotations are provided, so the description carries full burden. It discloses that the tool returns min/max lat/lng and centroid, and that it is a cheap operation without geometry serialization. While it doesn't elaborate on error cases or side effects, the lack of destructive behavior is implied. The description adds value beyond the schema by explaining the output format and performance characteristics.

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 consists of two well-structured sentences. The first sentence states the purpose, and the second provides actionable guidance on using the output. Every phrase adds value with no redundant or unnecessary 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?

For a simple tool with one parameter, comprehensive schema coverage, and an existing output schema, the description is complete. It explains what the tool returns, how to use the result, and how it compares to a related sibling tool. No significant gaps for an agent to misinterpret.

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% for the single parameter 'code', with a detailed description including an example and case-insensitivity note. The tool description does not add additional semantic information about the parameter beyond what the schema already provides, so baseline score of 3 is appropriate.

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 the tool gets the bounding box and centroid for a boundary using an ONS census code, specifying the verb 'Get', the resource 'boundary bbox/centroid', and the identifier type. It differentiates from siblings by noting it is cheaper than get_boundary_geojson_by_code and returns bbox values for use in other functions.

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?

The description explicitly advises when to use this tool: for spatial queries needing bounding box, and directs to pass values to sightings_in_bbox() or geographic_summary(). It contrasts with the alternative get_boundary_geojson_by_code() by noting it is cheaper because no geometry is fetched or serialized, providing clear usage guidance.

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