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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world behavior. The description adds a genuine behavioral detail — the Open Food Facts then Open Beauty Facts lookup chain — which explains result provenance, but it omits what happens when a barcode is not found and does not describe rate limits or the verdict shape.

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?

Three short sentences, front-loaded with the purpose before the mechanism. The opening 'Halal or Not.' fragment largely duplicates the title, which is minor waste, but the rest is efficient.

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 carries the burden of conveying return values, yet 'checks its ingredients' does not explain the halal verdict, confidence, or possible error results. For a single-parameter tool this is workable but leaves the agent guessing about output.

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%; the 'barcode' parameter is fully documented in the schema with accepted formats (EAN-13, EAN-8, UPC). The description adds no syntax or format meaning beyond that, so the baseline of 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?

States a specific verb and resource ('check a product by barcode') and even names the data sources and the ingredient check. It is clearly distinguishable from siblings like check_ingredients (ingredient text) and search_products (name search), though it never explicitly contrasts itself with them.

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?

The barcode-centric phrasing implies the triggering condition (you have a barcode), but there is no explicit when-to-use, when-not-to-use, or named alternative such as check_ingredients for non-barcode input. Usage must be inferred.

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