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

Beyond the readOnly/idempotent annotations, the description discloses a critical behavior: final_price is always null, verified with a 0/100 sample, and num_bids is the closest demand signal. This saves an agent from misinterpreting null prices and sets accurate expectations for the returned data. It also cites the source URL, adding traceability.

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 front-loaded with the core purpose and follows with a high-value caveat, a routing instruction, and a source. The second sentence is somewhat verbose, including sampling statistics (0/100, 60+ bids) that could be trimmed, but every clause carries useful information and nothing is redundant.

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?

For a search tool with no output schema, the description lists the key returned fields, explains the price null behavior, and provides the data source. It does not spell out the exact output format, but the field enumeration and annotations (readOnly, idempotent) give an agent enough to call it correctly and interpret results.

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?

Input schema covers 100% of parameters with clear descriptions (query, page, limit), so the baseline of 3 applies. The description does not add parameter-specific detail beyond what the schema states; it only contextualizes that the search is over sold lots, which is a subtle relationship but not new semantics for any individual parameter.

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 opens with a specific verb and resource: 'Search CONFIRMED-SOLD equipment lots on bigiron.com for comps', then enumerates the returned fields (title, make/model/year, quantity, seller, location, close date). It explicitly contrasts with bigiron_search ('for current asking prices instead'), making the tool's scope unambiguous relative to its closest sibling.

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 gives an explicit routing instruction: 'Use bigiron_search for current asking prices instead.' It also sets usage context with 'for comps' and warns that the hammer price is not exposed, so agents know this tool supplies demand signals rather than realized prices. The when/when-not guidance is direct and actionable.

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