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

Annotations already cover read-only safety and open-world semantics. The description adds exact-match behavior, the JSON-LD source for SKUs, and the one-argument constraint, which go beyond annotations. It does not describe error behavior when no match is found, but that is minor for a read-only resolver.

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?

The description is three short sentences, each earning its place: purpose first, usage guidance second, operational constraint last. There is no filler or repetition of schema details.

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 simple two-parameter resolver with no required fields and no output schema, the description gives everything an agent needs: exact input identity, the result (productId), the preferred scenario over search_products, and the mutual-exclusivity constraint. Missing error details are negligible here.

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?

Although schema descriptions cover both parameters, the schema has required: [] and would not convey mutual exclusivity. The description's 'Provide exactly one argument' clarifies that sku and url are alternatives, and it adds useful source context for extracting the SKU from JSON-LD. This is critical semantic information beyond the schema.

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 clearly states a specific verb and resource: converting an exact SKU or URL into a productId. It also differentiates itself from search_products by emphasizing exactness, so an agent can distinguish the tools.

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?

Explicitly says to prefer this tool over search_products whenever an exact SKU or URL is available, and explains why: search is approximate, this is not. It also mandates exactly one argument, removing ambiguity about invocation.

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