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

Annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, so safety is fully covered structurally. The description adds real context on what the comparison surfaces (price, rooms, schools with Ofsted grades, stations, amenities, agent), which helps an agent predict the payoff of calling it. It omits anything about the freshness/limitations of the underlying listing 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?

A single front-loaded sentence: trigger condition first, then the comparison dimensions, then the input in a short closing clause. No filler, no repetition of the title.

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 the description is not obliged to enumerate return values, yet it still orients the agent on comparison dimensions. Trigger, scope, source of ids and read-only nature are all covered; nothing needed to invoke it correctly 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% and the schema itself declares minItems=2/maxItems=4, so the parameter is already fully documented. The description's "Takes the homes' ids" and "two to four homes" only restate that constraint without adding syntax, ordering or error-handling meaning. 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?

Specific verb (compare) plus resource (homes) with explicit scope: two to four homes, side by side, on named dimensions. It is immediately distinguishable from search_homes (find listings) and get_home (single home detail).

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?

"Use this when the user wants to compare..." gives a clear triggering condition and ties the source to search_homes results, which is genuine routing guidance. It does not, however, state when not to use it (e.g. single-home lookups should use get_home) or what to do if the user hasn't searched yet.

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