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

Annotations already declare readOnly/idempotent/non-destructive, so the safety bar is low. The description then adds genuine value beyond that: the per-ingredient result fields, duplicate detection across products, the 'same rules engine as the Verateca site', the 12-item cap, and the explicit non-coverage of drug interactions.

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 core action and packed with dense, useful detail without filler sentences. It runs long as a single block, but essentially every clause carries information an agent needs.

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 must describe return values and it does so thoroughly — daily total, applicable limit, share of limit, status enumerations, contributing products, and duplicates. Combined with the stated cap and exclusions, an agent has everything needed to call and interpret it.

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%, so the schema already documents product_id format, the label-dose default, and the ISO country code. The description adds only marginal meaning (up to 12 products, country limits ordered first), so the baseline 3 applies.

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 precise verb-plus-resource: it sums each ingredient across up to 12 products and compares daily totals against the adult upper limit. This is much richer than the title, though it never explicitly contrasts itself with the sibling compare_products, which an agent could reasonably confuse it with.

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?

Use context is clear — checking a stack of products taken together, with the boundaries spelled out (up to 12, limits of the person's country come first). It even states a scope exclusion ('Interactions with medicines are not checked'), but gives no explicit routing guidance against sibling tools like compare_products or get_ingredient.

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