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

Even though readOnly/openWorld/idempotent are already in annotations, the description adds genuinely new behavioral context: it is temporary, heavily rate-limited, rejects UPRNs/coordinates, and preserves evidence, uncertainty, and not_found_in_source semantics. Nothing in the description contradicts the annotations.

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 short sentences, each carrying distinct information: accepted input, explicit exclusions, and result semantics. The most important operational warnings are front-loaded, and there is no filler.

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 demo with no siblings, the description covers accepted input, exclusions, rate limits, and semantic preservation of results. The absence of an output schema means the exact return shape is not specified, but the stated semantics give enough orientation for correct invocation.

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?

The schema already documents both parameters, including the response_mode enum and default, so the baseline is 3. The description adds extra meaning for the address parameter by excluding UPRNs and direct coordinates and requiring a postcode. response_mode is left to the schema, which is acceptable given its full documentation.

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 title clearly names the operation ('check English property planning constraints') and the description reinforces the input domain, but the description itself only calls it an 'evaluation' rather than explicitly stating what is being checked. There are no siblings, so no differentiation burden, but the purpose is fully clear only when title and description are read together.

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 explicitly says to use an address with a postcode and states that UPRNs and direct coordinates are not accepted, giving clear when-to-use and when-not-to-use guidance. The temporary-demo and heavy-rate-limit warnings additionally signal that this should not be treated as a reliable production service.

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