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

Annotations already cover the safety profile (readOnlyHint=true, openWorldHint=true), so the bar is lower. The description adds genuine scope disclosure beyond annotations: it lists the returned fields, notes that hammer/realized price only exists 'once sold,' and explicitly excludes full description prose, condition reports, and extra images. It does not mention auth or rate limits, but the field-scope disclosure is substantive.

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 purpose and returned fields, then exclusions, then routing alternatives. Every clause carries information and the sibling list, while long, is functional rather than filler.

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 description is not obligated to explain return values, yet it still names the returned fields and, more importantly, the fields that are deliberately absent. Combined with routing and the read-only/open-world annotations, an agent has everything needed to call it correctly; only the explicit trigger condition is left implicit.

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 documents both parameters with examples ('32001', '2'). The description merely restates the parameter names without adding format, valid-range, or sourcing guidance, so the schema does the heavy lifting and the baseline of 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 (Fetch) plus resource (one Bonhams lot) plus an enumeration of the exact fields returned (normalized title, estimate, hammer/realized price, sale date, category, department, lot number). It clearly distinguishes itself from sibling tools by naming bonhams_lot_search, bonhams_auction_search, bonhams_auction_detail, and bonhams_auction_lots.

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?

Explicitly routes the agent to the four sibling tools for their respective purposes (finding lots, finding auctions, one auction, an auction's lots), which serves as strong when-not guidance. It stops just short of stating the positive trigger (e.g., 'call this once you already hold an auction_id and lot_number'), which the required-param structure implies but the text never says.

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