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

Annotations already declare readOnlyHint, idempotentHint and non-destructive, so safety is covered. The description adds genuine behavioral context beyond that: accepted id variants (SKU, numeric id, barcode, product link, any case), the rejection of product names, and error-on-unknown/retired product rather than guessing. This is valuable failure-mode disclosure.

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 trigger condition, then id semantics, then error behavior, then the sibling alternative – each sentence carries distinct information. It is slightly dense and runs long, but no sentence is redundant with the schema or annotations.

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 single-param read tool with an output schema, the description covers everything the agent needs: when to use it, valid id forms, the name-not-accepted caveat, error behavior, and the alternative tool. Return-value documentation is rightly omitted since an output schema exists.

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 coverage is 100%, so the baseline is 3, but the description meaningfully extends the schema: it clarifies the id accepts SKU/numeric id/barcode/URL in any letter case, that it matches ids surfaced by find_products, compare_products or the basket, and that a product name will not resolve. That goes well past the terse schema text.

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 names a specific verb+resource (fetch a product's full details: brewing, caffeine, taste, ingredients, allergy advice) and explicitly distinguishes itself from find_products (search) and compare_products (side-by-side). An agent can route to this tool without opening either schema.

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?

It states exactly when to call it ('whenever someone asks how to brew... caffeine, taste, ingredients or allergy advice'), names the prerequisite alternative for lookup (search with find_products first, since a product name won't work), and points to compare_products for multi-product comparison. When/when-not and alternatives are all explicit.

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