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

Beyond the readOnlyHint/openWorldHint annotations, it discloses the cost model ($0.002 USDC per successful call via x402), that failed calls are not charged, the upstream source (public JSON route behind yatco.com search), and a data-quality caveat ('values are as the brokers entered them'). Payment and provenance info an agent needs before invoking are all present.

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?

Front-loaded with resource and scope, then fields, pagination, provenance, and cost. Dense but nearly every clause carries information; the long field enumeration is the only slightly heavy part.

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?

Covers source, scope, filtering, pagination limits, returned fields, data caveats, and pricing — everything needed to call it correctly despite the output schema already describing returns.

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%, including page range and builder examples, so the description adds no parameter meaning beyond the schema. 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?

States the specific resource (yachts for sale on YATCO), the scope (~6,000 active listings), and the optional filter (builder, with examples). No sibling tool covers yacht listings, and the description makes the data source 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?

Explains that builder filtering is optional and defaults to all builders, and that results are paged 12 at a time. It doesn't state exclusions or point at alternatives, but no plausible alternative exists among the siblings.

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