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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. Beyond that, the description discloses the non-obvious exact-match behavior for bedrooms/bathrooms and states what fields are returned (address, rent, beds/baths, square footage, listing date). It adds meaningful behavioral context without contradicting annotations.

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?

The description is compact and front-loaded: purpose first, then filters, output, the critical exact-match caveat, and finally the distinguishing guidance. Every sentence earns its place, with no filler or redundancy.

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?

Given 12 parameters, a fully documented schema, and no output schema, the description supplies the missing contextual elements: what kinds of listings are covered, what the results contain, and how this tool differs from related rent-statistics and estimate tools. An agent has enough information to invoke it correctly.

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%, so the baseline is 3. The description adds value by grouping parameters into three mutually exclusive search modes (city+state, ZIP, latitude/longitude radius) and reinforcing the exact-match semantics beyond the schema's per-parameter notes. This helps an agent choose the right parameter combination.

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?

Description states a specific verb ('Search'), a specific resource ('ACTIVE rental listings' from RentCast's feed), and a clear scope (homes/apartments currently for rent in the US). It explicitly differentiates from sibling tools by noting it is unlike area rent statistics or single-address rent estimates, making selection 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?

The description explicitly states when this tool should be used: 'the tool for find homes/apartments for rent near X'. It also names exclusions ('unlike area rent statistics (HUD Fair Market Rents) or single-address rent estimates') and gives a concrete usage caveat for exact-match bedrooms/bathrooms filters ('for 3-4 beds call twice').

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