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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior, so the safety profile is well covered. The description adds value by disclosing the response contents—photos, rating, delivery/payment facts, buy-now link—which is important since there is no output schema. The described behavior is fully consistent with the annotations.

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?

A single sentence with the scope front-loaded ('Everything about one product') followed by a dense, comma-separated field list. There is no filler and no repetition of schema or annotation information.

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 two-parameter read-only tool, the combination of schema (100% parameter coverage), annotations (read-only/idempotent), and the field-list description gives an agent everything needed to call it and understand the return. The main gap is absence of explicit guidance about when to choose this over narrower siblings, which is a minor omission for a simple detail endpoint.

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%, and both lang (enum with meaning) and slug (from search_products) are already documented in the schema. The description adds nothing about parameter format or defaults beyond what the schema provides, so the baseline 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?

The description opens with 'Everything about one product' and enumerates the exact fields (description, price, availability, age range, brand, photos, rating, delivery/payment facts, buy-now link), making the verb+resource and scope explicit. It clearly refers to a single product rather than lists or store-level data, but it never names a sibling or states what it is not, so sibling differentiation is implicit in the field list.

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 field enumeration implies the tool is the go-to for a complete product detail view, while targeted siblings like check_availability, get_shipping_quote, and create_cart_link cover single aspects. There is no explicit when-to-use or alternatives statement; the closest guidance is the schema hint that slug comes from search_products. That makes usage context discoverable but not proscriptive.

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