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

With readOnlyHint and openWorldHint already declaring the safety and reach profile, the description adds meaningful context by disclosing the data source ('the product page's structured data') and the field coverage. It does not mention error behavior for invalid SKUs or rate limits, but for a read-only detail lookup with an output schema that is a minor gap.

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 sentences, front-loaded with the core purpose and followed by sibling routing. Every clause earns its place and no space is wasted on restating the tool name or title.

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 single-SKU lookup with a fully documented input schema, existing annotations, and an output schema, the description supplies everything else an agent needs: what is retrieved, from where, and which sibling tools to use for adjacent tasks. Nothing required to invoke 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?

The description never mentions the single 'sku' parameter, but schema description coverage is 100% and the schema itself explains that it is a required numeric Best Buy SKU obtainable from bestbuy_category or bestbuy_search results. The baseline of 3 is appropriate when the schema already carries full parameter documentation.

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 states a specific verb ('Fetch') and resource ('Best Buy product details'), then enumerates the exact fields returned: model, price, availability, rating, and category breadcrumbs. It also names the sibling tools it is not, so an agent can distinguish it from bestbuy_search, bestbuy_product_related, bestbuy_product_reviews, and bestbuy_product_questions 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?

It gives explicit routing for the surrounding workflow: use bestbuy_search or bestbuy_category to find products, bestbuy_product_related for similar items, and bestbuy_product_reviews or bestbuy_product_questions for customer feedback. This leaves little inference about when to call this tool versus its alternatives.

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