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

Goes well beyond the readOnlyHint/openWorldHint annotations: it discloses the paid-call model ($0.002 USDC), the x402 payment rails (Base, Solana, Arc), the critical fact that failed calls are not charged, and a hard data cap ('up to about 300'). Cost and payment/auth requirements are exactly the behavioral context annotations cannot convey.

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?

Three sentences, front-loaded with the resource and scope, then filters, then pricing. The long field enumeration is slightly redundant against the output schema but still earns its place as a quick capability summary.

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, the return field list is bonus rather than necessity, and the description covers scope, filters, cost and result cap. It never explains how to go beyond the ~300 listing ceiling (no offset/pagination) or result ordering, which is the main residual gap for a listings tool.

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 all seven parameters are already documented; the description only restates the filter roles (price range, minimum bedrooms) and the type options. It adds the approximate 300 ceiling on limit, but nothing about format, ranges or interactions beyond that. Baseline 3 applies when the schema does the heavy lifting.

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 verb+resource+source ('Homes for sale on CENTURY 21 (US) in a city') and enumerates the returned fields (address, ZIP, coordinates, price, beds, baths, sq ft, type, photo, listing count). Naming the source portal and the US scope is what lets an agent distinguish it from the many sibling listing tools (zillow, redfin_property_listings, remax, estately).

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?

Gives clear scoping context (US, city-level search) and explains how to use the type/price/bed filters, but never states when to choose this over realestate_zillow, realestate_redfin_property_listings or realestate_remax, nor any when-not conditions. Usage is implied by the source name rather than spelled out.

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