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

With no annotations, the description carries the full burden and does well: it discloses that this is a human handoff, that no order is placed and no payment is taken, and that the returned link differs by product type (own checkout vs retailer buy link). Auth, rate limits, and URL formatting are unstated, keeping it short of a 5.

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 before the negative constraint. The first sentence is dense but every clause (own vs affiliate, cart vs product) carries operational meaning; nothing is wasted.

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?

There is no output schema, so the description must convey the return value, and it does: one or more links, whose target depends on whether the product is own or affiliate. It stops short of stating the link format or whether multiple links can be returned together for a mixed cart.

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 parameter ('product') is already documented in the schema as 'one product instead of the cart'. The description's parenthetical '(or one product)' restates the same default-versus-override semantics without adding format or scope detail, so baseline 3 applies.

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?

Names a concrete resource ('the link(s) where a PERSON completes the purchase') and enumerates the distinct link targets for own products versus affiliate products. An agent can distinguish this from siblings like cart, product, or store 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?

Specifies the trigger context ('for this session's cart (or one product)') and implicitly frames the boundary by stating the server never places an order or takes payment, which tells the agent not to use it as a purchase action. No explicit alternative tool is named, so it falls short of a 5.

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