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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so the safety and openness profile is settled. The description adds the data source (REP27's catalogue) and the shape of the answer, but its return-value detail overlaps with the existing output schema and it says nothing about rate limits, auth, or result ranking beyond 'best matches'.

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?

A single front-loaded sentence opens with the verb and resource before the parenthetical examples and the return clause. It is dense with enumerations but every clause carries information; only mild trimming would be possible.

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 two-parameter, read-only lookup with full schema coverage, annotations, and an output schema, an agent has everything needed to invoke it correctly. The only shortfall is the missing routing guidance relative to check_obligations.

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% for both parameters (lang and product), including examples and the ISO 639-1 language hint, so the schema carries the semantics. The description contributes no additional parameter meaning, which makes the baseline 3 correct.

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 specific verb and resource (searches REP27's product-category catalogue) and enumerates both the domain (toys, cosmetics, electronics…) and the payload returned (EU legal figure and REP27 service). The title adds a user-facing framing that helps an agent match intent, but it never explicitly contrasts with the closest sibling, check_obligations.

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?

There is no when-to-use or when-not-to-use guidance. The description never explains the boundary with check_obligations (which also concerns regulatory requirements) or when the agent should prefer this lookup over that one, so selection between siblings is left to inference.

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