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

Annotations already declare readOnly, idempotent, non-destructive and open-world, so the safety profile is covered. The description adds genuinely new context: the metered pricing model (free within daily allowance, then $0.001 USDC per call via x402) and a note that WKT is optional and capped.

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 tight sentences, front-loaded with the core retrieval semantics and followed by pricing. No wasted words and every sentence earns its place.

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?

An output schema exists so return formatting need not be explained, and the description covers identity, the optional geometry flag, and the cost model. It is nearly complete, missing only explicit routing guidance against the dataset-specific siblings.

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 both parameters are already documented in the schema, including the 'capped' WKT note. The description restates the optional-WKT behavior without adding syntax or format detail, so the baseline 3 is appropriate.

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 (retrieve) and resource (one planning.data.gov.uk entity from any dataset) keyed by entity number, which is clear and distinguishable from the dataset-specific siblings. It stops short of explicitly contrasting itself with those siblings (e.g. spatial queries by area), 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?

The description implies you need an entity number but gives no explicit when-to-use, when-not-to-use, or alternative routing against the many dataset-specific uk-planning__* siblings. The only usage-adjacent content is pricing, which does not help an agent select the tool.

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