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

Annotations cover the safety profile (readOnlyHint, openWorldHint), and the description adds non-obvious behavioral constraints: the URL must be a full public product-page URL for a Stencil storefront, and output is 'normalized.' It does not mention auth, rate limits, or failure behavior, 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?

Two tight sentences, front-loaded with the action and resource, followed by the input constraint and the alternative. No padding, though the constraint sentence could be marginally tighter.

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-URL read tool with an output schema (which handles return-value explanation) and annotations covering safety, the description supplies everything an agent needs: what it returns, the accepted URL form, and the sibling to use instead for search.

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 single URL parameter is already documented, giving a baseline of 3. The description adds meaning beyond the schema by specifying the 'full public product-page URL' requirement and the Stencil-specific constraint that the schema gloss does not convey.

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 ('Returns normalized product detail from a public BigCommerce storefront product page') and clearly distinguishes itself from the search sibling. An agent can tell this is a detail-by-URL fetch versus bigcommerce_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?

Explicitly routes the agent to bigcommerce_search for searching, which is a concrete alternative. It does not state explicit when-not conditions (e.g., that you must already have a product URL, or when to prefer bigcommerce_category), so it stops short of full routing guidance.

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