upc_lookup

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

The annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile needs no restating. The description adds nothing beyond that: it says nothing about not-found behavior, whether it hits a paid/rate-limited external service, or what the response looks like.

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?

One short sentence, front-loaded with the verb and resource, with no filler. Nothing is wasted.

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 one-parameter read-only lookup this is close to sufficient, but with no output schema the description should at least say what a miss looks like and how it differs from upc_search. Two small additions would make it complete.

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% for the single 'upc' parameter, and the description's 'UPC/EAN barcode number' merely restates the schema text. No extra meaning (formatting, hyphens/check digits, fallback behavior) is added.

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 specific verb and resource ('look up a product') and scopes it to exact-identifier lookup by UPC/EAN barcode. That implicitly separates it from the sibling upc_search (keyword search), but the sibling is never named, so the distinction must be inferred.

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 framing implies the case to use it (you already have a barcode number), but there is no explicit when-to-use / when-not-to-use guidance and no pointer to upc_search for name-based lookups. Adequate only by inference.

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