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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds substantive behavioral context: the authoritative sources consulted (Annexes II–VI, Hotlist, ASEAN Directive, etc.), the jurisdictional boundaries, and that the glossary is a specific edition ('last published edition'). It omits freshness/versioning caveats and error behavior, keeping it short of a 5.

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 answer to 'what does this do' in the first clause, then coverage, then exclusions. The regulation enumeration is long, but each item is a genuine coverage claim rather than filler; a mildly tighter grouping could shorten it without loss.

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 an output schema present, return-value documentation is unnecessary, and annotations cover safety. The description supplies scope, source authority and exclusions – everything needed to decide to call it. The residual gap is the unexplained non-enum parameters, which the schema's sparse descriptions do not fully close.

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 50%, so the description carries some burden. It implicitly maps the jurisdictions enum by naming the specific regime for each bloc (EU, UK, US, Health Canada, ASEAN, Japan) and hints at product_type via 'product-type conditions', but it says nothing about the 'function' enum, 'application', or 'for_children_under_3', which are left to the schema alone. Partial compensation warrants a baseline 3.

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?

Opens with a specific verb and resource ('Checks whether a cosmetic ingredient is banned, restricted or permitted') and enumerates the outputs it returns (INCI name, max concentration, product-type conditions, label warnings). The scope sentence pinpoints the exact regulatory domains covered, which cleanly separates it from siblings like check_chemical_substance or check_food_additive_or_ingredient.

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?

Gives an explicit boundary: 'Not intended for food, medicines or general chemical restrictions (the food, pharma and chemical tools cover those)' – naming both the exclusion and the alternatives. Combined with the coverage list, an agent can route an ingredient query to this tool or a sibling without guessing.

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