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

Annotations already declare read-only, idempotent, open-world, non-destructive behavior, so the safety profile is covered. The description adds genuinely non-obvious context: exact-match semantics with internal spaces preserved, a concrete example number, and the caveat that historical UDI records do not confirm current certificate validity or legal sale.

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?

Front-loaded with the primary usage cue, followed by the matching rule, the alternative tool, and a legal caveat. Every sentence earns its place, though the example number adds length that could be trimmed.

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 4-param, single-required read tool with no output schema, the description covers input semantics, routing, and a meaningful data caveat. Pagination behavior is only implied via the snapshot parameter rather than explained in prose, which is the remaining gap.

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 only 25%, so the description carries the burden for registration_no, which it does well (exact match, space preservation, example). However, limit/offset are undocumented in both description and schema, and only snapshot has a schema description, so compensation is partial.

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?

States a precise verb+resource: retrieval of China UDI products/models tied to a registration or filing number. It distinguishes itself from the sibling get_company_devices by input type (number vs. company name), so an agent can route correctly without opening schemas.

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 positions the tool relative to general web search ('use before general web search') and names the alternative for the company-name case ('use get_company_devices instead'). Both the when and the when-not are stated outright.

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