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

Annotations already establish readOnlyHint, openWorldHint, idempotentHint, and non-destructive behavior, so the description needs only light additional context. It adds federal/proximity-list behavior but no deeper caveats like default limits or result set 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?

Two short sentences with no filler. The main verb and resource are front-loaded, and the examples and unit clarification earn their place without duplicating the schema.

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 read-only list-by-coordinates tool with complete schema descriptions and safety annotations, the description is sufficient for selection and invocation. It could mention that non-proximity facility searches belong in recreation_search_facilities, but that is more routing guidance than missing invocation detail.

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 baseline is 3. The description's 'Radius is in kilometers' reinforces the radius_km parameter note but does not add meaning beyond the schema. Lat/lon as center coordinates is also already documented.

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 ('list') and resource ('federal recreation facilities') with a clear geospatial scope (radius around a coordinate). It does not explicitly distinguish itself from sibling tools like recreation_search_facilities or recreation_search_campsites, so it falls just short of a 5.

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?

Gives concrete use cases ('campgrounds near a property', 'fishing spots near a city') that clearly signal the intended proximity-search scenario. It does not explicitly state when not to use it or name alternatives, so it is a 4 rather than 5.

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