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

Annotations already cover safety (readOnly, idempotent, non-destructive, closed-world), so the description's job is interpretive context — and it delivers the critical caveat that bands describe an area's likelihood, not a particular property. It adds a real usage hazard the agent would otherwise misreport. It doesn't discuss data coverage gaps (e.g. England-only) or missing-band cases.

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 sentences, no filler, with the primary output described first and the UPRN variant second. The caution lands last where it will be read before the agent responds to the user.

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 and full schema descriptions, the description needn't explain return values, and it correctly focuses on interpretation. What's missing is edge-case behavior — what happens when no flood data exists for the area, or geographic limits on the dataset. Adequate but not exhaustive.

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 100% and the uprn parameter already documents 'A home's UPRN for its own bands; without it, only the area's land bands,' so the description largely restates structured data. The one marginal addition is framing UPRN results as still not property-specific, which changes how results should be presented. 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?

The description names the concrete resource (flood bands for land, split into rivers/sea and surface water) and the second mode activated by a UPRN. That is specific enough that an agent can distinguish it from metrics siblings like get_area_metric or get_area_overview. It stops short of explicitly contrasting itself with any sibling, which keeps it at 4.

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 gives clear routing logic: use this for area-level bands, and if the user wants one specific address, send them to the Environment Agency check. That is an explicit 'do not use for this' condition. It doesn't state when to prefer this over other area-evidence tools (get_area_evidence_pack, get_area_metric), so it isn't a full 5.

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