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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world). The description goes further by disclosing the ordering behavior (the requested country's upper limit first, then other countries), the provenance metadata attached to limits (type, source, date checked), and the inclusion of a containing-product count — real behavioral context beyond 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?

A single front-loaded sentence that leads with the core action and then lists the returned fields. It is dense and slightly run-on, but nearly every clause carries distinct information about the response shape.

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, the description carries the burden of describing returns and does so substantively — forms, shares, limits with type/source/date, sources, product counts. Safety and idempotency are covered by annotations and all three params are documented, leaving little an agent still needs to know.

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% and the schema already documents id, name-as-alternative, and the country default with its "limits first" effect. The description's mention of country ordering repeats what the schema already states, so it adds no meaning beyond structured fields.

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+resource ("Returns one substance of the register") and enumerates the payload: forms, element share, country limits, sources, product counts. This clearly separates it from the product-oriented siblings (get_product, search_products), though it never names an alternative explicitly.

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 only implied — an agent can infer this is the lookup for a single substance by id or name, but there is no statement of when to prefer it over search_products or get_product, nor any prerequisite or exclusion guidance.

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