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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint. The description adds valuable behavioral context beyond those: the tool returns a URL and checklist rather than performing verification, and it supports only three labs. This aligns with the annotations and gives the agent an accurate mental model of observable behavior.

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 tight sentences with no filler. The return value is front-loaded, supported labs are stated compactly, and the final sentence clarifies the tool's limitation. Every sentence earns its place and the description is highly scannable for an agent.

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 simple two-string-parameter read-only tool with rich annotations and no output schema, the description is complete. It states what is returned, which labs are supported, and what the tool never does. The absence of an output schema is not a gap because the description succinctly describes the return content and the tool has no complex hidden behavior.

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 the schema already documents lab and report_number with case-insensitivity and report placement. The description reinforces that lab is limited to GIA, IGI, or GCAL, which is useful, but it does not add substantial meaning beyond the structured schema. Baseline 3 is appropriate.

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 uses a specific verb ('Returns') with a clear resource: the official verification URL and a three-step checklist for confirming a grading report. It also explicitly states what the tool does not do ('never verifies anything itself'), which sharply distinguishes its purpose from any verification-performing tool and from siblings like get_product or search_encyclopedia.

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 clear context: use this to confirm a diamond grading report with the issuing lab for GIA, IGI, or GCAL. It does not name explicit alternatives or provide when-not-to-use conditions, but the scope is sufficiently clear and no sibling tool appears to overlap, so a minor deduction for missing explicit exclusions.

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