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

Annotations already declare readOnlyHint=true and destructiveHint=false, so no contradiction. The description adds useful behavioral context beyond annotations: the operation costs 1 credit, and the caller must supply exactly one of seller_id or url. It does not detail error behavior or pagination, but the core safety profile is covered by 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?

The description is compact and front-loaded with the tool's core output, then usage guidance, then the critical mutual-exclusion constraint and credit cost. There is no filler or repetition; every sentence contributes to selection or invocation.

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 4-parameter tool with no output schema, the description covers what is returned, when to use it, which alternatives to prefer, the required argument pattern, and the cost. Nothing an agent needs for ordinary invocation 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?

Schema description coverage is 100%, so the baseline is 3. The description adds meaningful parameter relationship guidance: seller_id and url are mutually exclusive, and get_product_offers can resolve a seller_id. This goes beyond the per-property schema descriptions.

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 names a specific resource (Amazon merchant identity) and returns legal business name, address, and feedback trends. It explicitly positions itself as the supplier-verification tool and distinguishes itself from get_seller_products and get_seller_feedback, so an agent can select it correctly.

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 explicitly states when to use the tool ('who is this seller?', 'is this merchant legitimate?', compliance/invoicing) and names alternatives for adjacent tasks (get_seller_products for items, get_seller_feedback for individual reviews). It also gives an input rule and points to get_product_offers as a way to discover the seller_id.

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