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

Annotations already establish readOnly, idempotent, non-destructive behavior. The description adds valuable context beyond that: the listing must belong to the bound seller, and it enumerates the included content (description, stock/reserved counts, spec values, moderation state). The refusal condition is a meaningful behavioral disclosure not present in the annotations.

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 with no filler. The core action and scope are stated first, followed by the returned content and the ownership refusal condition. Every clause earns its place.

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 one-parameter, read-only tool with rich annotations and full schema coverage, the description covers the purpose, authorization constraint, and return content. There is no missing information an agent needs to invoke it correctly.

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 product_id parameter is already described as 'UUID of the listing to fetch.' The description adds no new parameter-level detail, so it neither improves nor harms the schema's explanation. 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?

The description uses a specific verb ('Fetch') and resource ('a single listing the bound seller owns'), and clearly scopes it to the seller's own listings. It distinguishes itself from list-style siblings like seller_list_listings and read-only catalog tools by naming the ownership constraint and the returned content. The refusal condition further pins down what the tool is and is not.

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 clearly identifies when to call this tool: to fetch one specific listing owned by the bound seller. It does not explicitly name alternatives or state when-not-to-use, but the ownership condition and the 'single listing' scope make the intended use reasonably inferable.

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