Find castles near a point

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

Without annotations, the description discloses key behaviors: results are sorted by distance, include 'distance_km', and the radius defaults/max are specified. It doesn't mention idempotency or side effects, but the listing nature implies read-only operation.

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 concise sentences with essential information front-loaded. No filler or redundancy.

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?

Given no output schema, the description adequately describes the output format (distance_km, sorted). It mentions the default/max radius and provides usage guidance. Minor omission: no mention of the 'limit' parameter's default behavior.

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 40% (limit and radius_km have descriptions; latitude, longitude, category do not). The description adds radius defaults but does not clarify the missing parameters. It provides marginal value beyond the schema.

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 specifies the verb 'List' and the resource 'landmarks within a radius of a WGS84 coordinate', and clarifies the ordering ('nearest first'). It provides a concrete usage example ('For "castles near <place>"...'), which distinguishes the tool from siblings like 'search_castles' that likely use text-based queries.

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 gives explicit instructions for the common use case ('geocode the place yourself, then call this'), which aids selection. While it doesn't explicitly state when not to use this tool, the guidance is clear and actionable.

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