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

Annotations already cover the safety profile (readOnlyHint, destructiveHint false), so the bar is lower, and the description still adds genuine behavior: outside local planning data the result falls back to world maps and is flagged rough: true. That fallback and its output marker are things the annotations cannot convey. It omits the response shape and any performance caveats, keeping it from a 5.

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?

Four tight sentences, front-loaded with the purpose and followed by input modes, data-source caveat, and safety note. No filler, though the trailing 'Read-only; nothing is saved' largely restates the readOnlyHint annotation.

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?

With four optional parameters, a nested polygon object, and no output schema, the description still tells the agent what comes back (habitats, amounts, protection, distance to target, rough flag) and how inputs combine. Nothing needed to call it correctly is missing.

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 75%, and radius_km has no schema description, so the description usefully supplies the pairing rule: polygon OR point plus radius_km, which tells the agent the parameters are alternatives rather than cumulative. It does not explain units or limits on radius_km or polygon validity beyond GeoJSON/WGS84 already in 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 gives a specific verb and resource ('check an area against its protection targets') and enumerates the outcome dimensions: habitats held, amount of each, protection status, and distance from target. That is far more informative than the title alone. It stops short of naming any sibling, so an agent must infer the boundary with look_in_area or get_features on its own.

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?

'Give a polygon, or a point and radius_km' defines acceptable input shapes but not when this tool is preferable to siblings like look_in_area, look_here, or get_features. Usage context is implied by the word 'targets' rather than stated as a selection rule.

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