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

Annotations already declare readOnly, idempotent, non-destructive, and openWorld, so safety is covered. The description adds value by disclosing the full set of fields returned ('in full: code, description...'), compensating for the absence of an output schema. It doesn't discuss error behavior for missing products, so 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?

A single sentence, front-loaded with the verb and resource, with the field enumeration earning its place by standing in for a missing output schema. No waste.

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 with no output schema, the description is nearly complete: it lists what fields are returned and identifies the resource. Missing only explicit guidance on unknown-id behavior and the relationship to list_products.

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?

Only one parameter and schema coverage is 100%, with the schema documenting the UUID format. The description's 'one product' confirms single-id lookup but adds no syntax or format beyond the schema. Baseline 3 is appropriate.

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 (fetch) and resource (one product) and enumerates the returned fields (code, prices, tax rate, stock, category), which clearly differentiates it from the sibling list_products.

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?

'Fetch one product' implies a single-record lookup by id, distinguishing it implicitly from list_products, but the description never explicitly says when to prefer this over the list tool or that it requires a known product_id.

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