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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds meaningful context beyond that: it states 'performs no new inference or aggregation', notes 'Coverage is limited to the available snapshot', and explains empty results and error behavior. These details enrich the agent's understanding of call outcomes without contradicting the annotations.

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, then flows into inputs, return behavior, and error conditions. It is succinct with no filler, though it repeats 'registration_no' twice (in 'Inputs' and 'Required'), which is a minor redundancy. Still, every sentence contributes critical information, earning a 4.

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 tool with four parameters and no output schema, the description is remarkably complete: it explains pagination, snapshot behavior, empty results, and error handling. It references 'source_class, provenance, snapshot, pagination and limits' as return elements, but does not detail the structure of each record, which would push it to a 5. Given the constraints, it is well-rounded and sufficient 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 description coverage is 100%, with each parameter already fully documented in the input schema. The description adds only marginal value on parameters, mentioning registration_no as required and hinting at pagination via 'paginated structured records'. It does not go beyond the schema's detailed parameter descriptions, so the baseline of 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 clearly states the tool's purpose: 'Find medical-device records associated with a registration or filing number.' It specifies a precise verb and resource, and the input registration_no makes the scope distinct from sibling tools that search by company or device. However, it does not explicitly name or differentiate from siblings, so it stops short of a 5.

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?

Usage is implied rather than explicit: the tool is for when you have a registration or filing number, and 'Required: registration_no' reinforces that. But the description provides no guidance on when not to use it or how it compares to alternatives like get_udi_company_products or search_udi_products. This matches the 'implied usage' level.

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