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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so safety and idempotency are covered. The description adds a genuine scope disclosure ('federal' facilities) and the radius unit, but says nothing about pagination, result ordering, or whether the radius is a hard cutoff. Adequate but not rich.

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, front-loaded with the core behavior before the use-case examples. The trailing unit note slightly duplicates the schema, keeping it from a perfect score, but nothing is wasted.

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 read-only, idempotent proximity list tool with a fully documented 5-parameter schema and annotations covering the safety profile, the description is essentially sufficient. With no output schema, a brief note on what a facility record contains or on default result size would have closed the remaining gap.

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% and every parameter (lat, lon, limit, activity, radius_km) already carries its own description with units and defaults. The description's 'Radius is in kilometers' merely repeats radius_km's schema text, adding no new meaning. 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?

States a specific verb (List), resource (federal recreation facilities), and scoping mechanism (within a radius of a coordinate), which is clear enough for an agent to distinguish it from keyword-based siblings like recreation_search_facilities. It never names those siblings, however, so the differentiation is inferred rather than explicit.

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 second sentence gives concrete usage context (campgrounds near a property, fishing spots near a city), which tells the agent the right scenario: coordinate-anchored proximity search. It stops short of any when-not guidance or explicit routing to the other recreation_* search tools.

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