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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety profile is covered. The description adds genuinely new operational context: the free daily allowance and the per-call x402 payment mechanism, which an agent needs in order to anticipate cost.

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 subject and scope, then pricing. No padding, though the '(2/3)' shorthand and the 'WKT (capped)' detail sit slightly at odds with a description this terse.

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 present, return values need no explanation, and annotations carry the safety profile. The description covers input modes and cost; it could still clarify what distinguishes Flood Zone 2/3 results or the meaning of the geometry cap, but nothing critical to invocation 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 are already documented. The description reinforces the two input modes ('By UK postcode or lat/lng') but adds no syntax or format detail beyond what the schema provides. 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+resource ('Planning flood zones (2/3) at a point') and clarifies the domain ('as published for planning decisions'), which usefully separates it from the uk-flood__* siblings that concern warnings and stations rather than planning zones. It stops short of naming an alternative directly, so the differentiation is inferential.

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 usage (point-based flood zone lookup for planning) and notes billing context ('Free within the daily allowance, then $0.002 USDC per call via x402'), but gives no explicit when-to-use vs when-not guidance and never points at a sibling such as uk-property__planning-constraints for bundled constraint checks.

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