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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds real value beyond them: unknown values stay null, stock is an aggregate warehouse figure that does not promise same-day pickup, and the endpoint is public with no auth. It stops short of noting rate limits or the aggregate's freshness, hence not a 5.

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?

Three short sentences, front-loaded with what is read and what it returns, then the two caveats (null semantics, stock interpretation), then access notes. No filler and nothing redundant.

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?

With an output schema present, the description need not explain return values; it still covers the access model, null behavior, and a meaningful interpretation caveat for stock. For a one-parameter read tool with full annotations, nothing an agent needs to call it correctly is missing.

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 the single product_id parameter is richly documented in the schema (including the 'not the SKU or basket item ID' disambiguation). The description adds nothing further about the parameter, so baseline 3 is correct.

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 (Read) plus the resource (a current product) and enumerates exactly what is returned: price, aggregate warehouse stock, and public characteristics. An agent can distinguish this from search_products (multi-result discovery) and get_product_reviews (reviews) without opening any 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?

The description gives usage-relevant context (public, no OAuth required) and a caveat about stock interpretation, but never states when to use this tool versus search_products or when not to call it. Usage is implied rather than explicit, so it lands at minimum-viable.

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