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

Annotations already establish readOnly/idempotent/non-destructive, so the description is free to spend its words on the response payload, which it does by enumerating the regulatory facts returned. It also implies a negative outcome path with 'if so', though it never says what comes back when the product is not authorised in that market.

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, front-loaded with the core action, and the second sentence adds a distinct payoff (the intended question shape) rather than restating the first. Nothing is wasteful.

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?

With no output schema, describing the returned fields is exactly the right compensation, and annotations cover the safety profile. The main remaining hole is the not-authorised case, which matters for interpreting a question phrased as a yes/no.

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 100%, including the locale enum and the ISO alpha-2 guidance for region, so the schema already carries the parameter burden. The description only adds the informal 'country Y' framing around region; it says nothing about locale or its fallback that isn't already in the schema.

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: 'Check whether a product is authorised in a specific market/region'. The returned fields (registration status, number, pack sizes, approved uses) sharpen the distinction from get_product, but no sibling is named explicitly, so an agent must infer the boundary rather than being told.

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?

Supplies a concrete usage scenario in natural language: 'can I use product X in country Y?'. That is a clear positive trigger, but there is no statement of when NOT to use it (e.g. for general product data, use get_product) and no mention of prerequisites such as needing a known slug vs. searching first.

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