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

The readOnlyHint and openWorldHint annotations already declare this is a safe, self-contained lookup, so the safety burden is covered. The description usefully discloses what the tool reports (land share, buildings, residents) and the rise-vs-year/scenario input modes, but adds nothing about default behavior, error cases, or data vintage. Adequate with annotations doing the safety lifting.

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?

A single compact sentence with the scope and the output metrics front-loaded, and the alternate input mode kept to a short parenthetical. No waste, though the parenthetical slightly interrupts the main clause.

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 read-only, zero-required-parameter aggregation tool with a fully documented schema and no output schema, the description supplies the key missing piece: what the returned figures represent. It needn't explain return format, and only the absence of sibling routing keeps it from a 5.

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%, with enum values and the default scenario and lang documented inline, so the schema carries parameter semantics fully. The description's mention of rise_m vs year+scenario mirrors what the schema already says and adds no syntax, units, or range detail beyond it. Baseline 3 is correct.

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 resource (island-wide flood impact for Singapore) and enumerates the computed metrics: share of land flooded, buildings reached, residents affected. The 'island-wide' scope contrasts with the area-level sibling area_impact, though no sibling is named explicitly, so it stops 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 parenthetical '(or a year and scenario)' hints at two input modes, but the description never states when to prefer this over area_impact, most_affected_areas, places_underwater, or check_address. No exclusions, prerequisites, or alternative-selection guidance are given.

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