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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false and destructiveHint=false, so safety is covered. The description adds context annotations cannot carry: the tool returns a verdict per school plus reasoning, and it is scoped to a single item. With no output schema, this return-shape disclosure is genuinely load-bearing, though nothing is said about verdict vocabulary or unknown-ingredient handling.

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?

Two tight sentences, front-loaded with purpose, then examples, then the return contract. No filler, no restatement of the title, and every sentence carries information the agent can act on.

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?

For a simple, read-only, two-parameter lookup whose annotations cover the safety profile, the description supplies purpose, input examples and output content. It stops short of explaining the 'context' enum's effect or what a verdict/school value can be, which slightly under-serves a tool with no output schema.

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, and the description's examples simply mirror the schema's own 'E471, carmine, gelatin or alcohol denat' wording. The 'context' parameter (food vs cosmetic, defaulting to food) is never mentioned, so the description adds no meaning beyond the 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 ('Explain one ingredient or E-number') and emphasizes the singular scope, which implicitly contrasts with the batch-oriented sibling check_ingredients. The examples ('E471', 'carmine', 'prawns', 'whey', 'alcohol denat') pin down the input domain, and it even names the output ('verdict for each school and the reasoning').

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?

No explicit when-to-use, when-not, or alternative selection is given; the agent must infer that this is the single-item lookup counterpart to check_ingredients. Usage is implied adequately by the examples and the 'one ingredient' framing, but no sibling is ever named.

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