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

Annotations already declare readOnly, idempotent and non-destructive, so the safety profile is covered. The description adds meaningful behavior beyond that: it caps results at five, explains the verdict plus 'say' line, and discloses the brand_statement resolution rule ('that statement decides it and is quoted'). It stops short of describing ranking or failure behavior.

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 action and scope, and every sentence carries information about inputs or returns. The second sentence is dense but earns its length by explaining the return shape and the brand_statement rule.

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?

There is no output schema, so the description must carry return-value context, and it does: match count, verdict per match, 'say' line, and brand_statement. Combined with full schema coverage and read-only annotations, an agent has enough to invoke it correctly; error/empty-result handling is the only omission.

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 both parameters are already documented in the schema, including the barcode example and country slugs. The description adds only the illustrative 'Haribo Starmix' example, so it sits at the baseline for a fully documented 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 ('Find products by name and check them', 'Searches Open Food Facts by name or brand') and describes the output shape (up to five matches, a verdict, a 'say' line). It does not explicitly name the sibling check_product_by_barcode, which also accepts a barcode via 'q', so the boundary is left slightly ambiguous.

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 implied by 'searches by name or brand' with an example query, so an agent can infer the lookup use case. However, there is no explicit when-to-use statement, no stated alternatives to check_product_by_barcode or check_ingredients, and no exclusion criteria.

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