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

With no annotations, the description carries the full burden and does disclose the critical trait: the server never places an order or takes a payment, so the agent must hand off rather than report a completed purchase. It also explains that multiple links can come back depending on product type. Gaps remain on auth requirements, whether links expire, and behavior with an empty cart.

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?

Front-loads the scope and the core meaning in the opening clause, then uses the closing sentence for the most important safety fact. Two sentences, no filler, though the middle enumeration of link types is dense enough to require a second read.

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-optional-param, no-annotation, no-output-schema tool, the description covers what comes back (links), the two product branches, and the non-transactional nature. It leaves only minor unknowns such as empty-cart behavior and link validity, which are not blockers to correct invocation.

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% and the single optional parameter is already documented as 'one product instead of the cart'. The description restates the same cart-or-product choice without adding format or selection criteria, 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?

States a specific resource ('the link(s) where a PERSON completes the purchase') and enumerates the two link types it can return: own-product product page/cart versus affiliate retailer buy link. The title's framing plus 'this server never places an order or takes a payment' distinguishes it from any sibling that mutates the cart, so an agent can tell it apart from cart/store without opening a 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?

The scope is implied well ('for this session's cart (or one product)'), so an agent can infer this belongs at the end of a shopping flow, but no sibling is named and there is no explicit when-not-to-use or handoff rule. Minimum viable implied usage rather than routing guidance.

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