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

Annotations already cover read-only/idempotent safety, so the description's job is edge-case disclosure and it delivers: it warns that LSOA-level values are borough averages (a provenance/fallback caveat) and that results are empty for studios or before rents are loaded. These are non-obvious behaviors an agent would otherwise misreport as real data.

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 with the metric front-loaded and caveats after. 'Borough averages per LSOA' is compressed to the point of ambiguity but no sentence is padding.

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 shape needn't be described, and the edge cases are covered. However, for a two-required-param lookup embedded among many similar metric tools, the absence of any routing guidance and of currency/timeframe context leaves real gaps.

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 the schema already documents both area_ids and bedrooms; baseline 3 applies. The description adds only an edge case ('empty for a studio'), and it slightly muddies things since bedrooms has a minimum of 1 — it does not clarify units, currency, or whether area_ids must all be the same geography level.

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 concrete verb+resource: median monthly rent by bedroom count for given areas, with the parenthetical '(the figure the site shows)' tying it to a known quantity. It does not name or distinguish itself from siblings like get_home_prices or get_area_metric, but the metric itself is unambiguous.

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?

There is no statement of when to use this instead of get_home_prices, get_area_metric, or rank_areas_by_metric. The agent must infer that this is the rent-specific lookup from the name alone; no exclusions, prerequisites, or alternatives are given.

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