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

The readOnlyHint=true annotation already establishes this as a safe read, and an output schema exists to carry the return shape. The description's field list (image, brand, price/availability, rating) confirms the returned data is normalized detail rather than raw HTML, which adds some context, but it discloses no failure modes, availability caveats, or freshness behavior beyond what annotations and the output schema provide.

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 sentences, no waste: the first front-loads what the tool returns, the second explains where the identifier comes from. Well ordered for an agent scanning for purpose first, parameter help second.

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-parameter read tool with an output schema and read-only annotations, the description covers purpose, contents, and how to source the id. Nothing essential is missing; only minor edge-case notes (e.g. invalid/missing UPC behavior) would push it higher.

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% and the schema already explains UPC as the last path segment of the product URL, so the baseline is 3. The description goes further by tying the value to a concrete external source ('also returned by kroger_search's products[].upc field'), which meaningfully helps the agent obtain a valid id.

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: it returns ONE Kroger product's normalized detail, then enumerates exactly which fields (title, description, image, brand, category trail, price/availability, rating). This clearly separates it from the plural kroger_products list tool and from kroger_search 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?

Gives concrete sourcing guidance: the upc comes from a product page's /p/ URL or from kroger_search's products[].upc field, which tells the agent this is a follow-up detail lookup to a search. It stops short of an explicit when/when-not contrast against siblings like kroger_products or kroger_product_reviews, so a 4 rather than 5.

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