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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint=false; the description adds valuable behavior beyond that: category is a product-title fan-in, matchedProducts distinguishes a true zero from a broken lookup, empty results never widen to all merchants, and verifiedBrand is backed by a KYB cascade. No contradiction with 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 dense but well-organized: action and modes first, then mode-specific semantics, return shape, category edge behavior, empty-result behavior, and usage guidance. Every sentence carries distinct information and there is no filler.

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?

With no output schema, the description provides the return shape and important edge cases. It covers all four parameters, the exactly-one constraint, empty-result behavior, and verified-merchant guidance, making it complete enough for an agent to call the tool 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 description coverage is 0%, and the description compensates fully: slug is an exact storefront URL, name is a case-insensitive substring over merchant names, category is a case-insensitive substring over product titles deduped to merchants, and limit caps the returned cards. It adds substantial meaning beyond the raw schema fields.

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 (find), a specific resource (droplinked merchant), and the three lookup modes: slug, name, and category. It also clearly distinguishes category matching from a normal taxonomy lookup by explaining the product-title fan-in behavior, which differentiates it from related find_* and search_* siblings.

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 instructs the agent to provide exactly one lookup key and explains each mode's matching semantics, plus the empty-result behavior. However, it does not explicitly name alternative sibling tools or state when-not-to-use this tool, so it stops short of full alternative routing.

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