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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds genuine behavioral detail beyond that: it discloses the differing return shape for herbal/other supplements (supplement, what_studies_looked_at, studied_amounts, ceiling, cautions, source instead of rda/upper_limit), the country=GB branch returning NHS amounts in a uk field, and the NIH fact-sheet link.

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?

It is front-loaded with the core purpose and example questions before the long enumeration of covered nutrients and supplements, and each sentence carries distinct information (scope, examples, coverage lists, alternate return shape, UK behavior). The exhaustive nutrient/supplement enumerations are heavy, but they serve recall for a lookup tool and are not purely redundant.

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 usefully compensates by naming the return fields and how they change between nutrient and herbal categories, plus the country variant. Coverage, examples and output shape are all present; only edge behavior (e.g., unknown or ambiguous nutrient names, relationship to the get_supplement sibling) is left unaddressed.

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% and both parameters are documented there, so the baseline is 3. The description adds only marginal semantics: it reinforces that name accepts forms like 'magnesium glycinate' and clarifies that country=GB also surfaces UK amounts plus NHS guidance in a uk field, which is slightly more than the schema's text.

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 states a specific verb+resource: it returns what a vitamin, mineral or supplement does, how much adults need, limits, cautions and food sources, backed by concrete example questions. It is clear about the scope of content returned. However, it never distinguishes itself from the closely-named sibling supplementcheck_get_supplement (or check_dose/check_stack), so an agent cannot disambiguate within the family from the text alone.

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 context is well established through example requests ('what does magnesium glycinate do?', 'how much vitamin D do I need?', 'what is creatine?'), which clearly signals informational/lookup queries. It does not, however, name an explicit alternative or exclusion (e.g., 'for safety/dose checking use supplementcheck_check_dose'), which matters here since 'is ashwagandha safe?' could plausibly route to a sibling.

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