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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered. The description adds one useful fact beyond them, that the response includes the product's page and outbound link, but says nothing about not-found handling or result shape beyond those fields.

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?

A single front-loaded sentence naming the resource, the key, and the returned payload with zero filler. Nothing could be removed without losing information.

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 one-parameter read tool with full annotations and a fully documented schema, the description covers purpose and hints at the return payload in lieu of an output schema. Missing only edge-case behavior such as an unknown slug.

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?

With one parameter at 100% schema coverage including a regex pattern and length bounds, the schema carries the semantics. "By its slug" confirms slug is the identifier rather than a name or ID, but adds no format detail, so baseline-plus 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?

"Get one affiliate product by its slug" gives a specific verb, resource, and lookup key, and "one" implicitly contrasts it with the list_* siblings. No sibling is named explicitly, so it falls short of the top mark.

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?

Usage is only implied: fetch a single product when you already hold its slug. There is no explicit when-to-use versus list_products or search_listings, and no stated prerequisite or failure behavior for an unknown slug.

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