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

Annotations declare readOnlyHint=true and openWorldHint=false, and the description does not contradict them. It adds useful behavioral detail by explaining what the tool reports: retailer listings, count, and price range, which goes beyond a bare 'look up certificate' statement.

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?

Two sentences with no filler. The action and identifier are front-loaded, followed by output summary and a practical use case. Every sentence contributes.

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 single-parameter, read-only lookup tool with no output schema, the description adequately covers the input, the useful output, and when to use it. It could be slightly stronger with an explicit alternative reference, but nothing critical is missing for correct invocation.

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 0%, so the description must clarify the parameter. It does so by defining certificate_number as a grading report number and naming accepted labs (GIA, IGI, HRD, GCAL), adding meaning beyond the schema's bare type and length constraints.

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?

The description states a specific action ('Find a diamond') and a precise resource/identifier ('grading report number'), listing accepted labs (GIA, IGI, HRD, GCAL). It clearly differentiates from siblings by emphasizing exact-stone lookup rather than broad search or market overview.

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 a clear use case: checking whether a quoted price is fair for a specific certificate number. It does not explicitly name alternatives or exclusion conditions, but the exact-stone framing implies when this tool is appropriate versus broader search tools.

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