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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds real context beyond that: the pricing model (free within the daily allowance, then $0.002 USDC per call via x402) and the meaning of the result. Return specifics are left to the output schema, which is reasonable.

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?

Three tight sentences: what it returns, how to invoke it, and the cost model. The core purpose is front-loaded and 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?

With an output schema handling return values and annotations covering the safety profile, the description needs only to state purpose, inputs, and cost — all of which it does. Nothing an agent requires 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 description coverage is 100%, so all five parameters (lat, lng, postcode, geometry, include_ended) are already documented in the schema. The description only reaffirms that a postcode or lat/lng pair is expected. Baseline 3 applies when the schema carries the detail.

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+resource test ('whether a point is inside a conservation area') and parenthetically explains the domain consequence (extra planning controls on demolition, trees, alterations). This clearly distinguishes it from sibling designations such as green-belt, listed-building, or sssi without opening any schema.

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?

It states the two accepted input methods ('By UK postcode or lat/lng'), which is useful invocation guidance, but gives no when-to-use/when-not conditions and names no alternative among the many uk-planning designation siblings. Usage is implied by the self-describing name rather than made explicit.

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