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

With no annotations, the description carries the full behavioral burden and does well for a read-only tool: it explains the different link types returned (product page, store cart for own products, retailer buy link for affiliate products) and explicitly states no order is placed and no payment is taken. It omits auth requirements and any rate/expiry caveats.

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 dense sentence with the scope front-loaded and the key non-charge guarantee trailing. It is slightly run-on due to stacked parentheticals, but nearly every clause carries 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?

No output schema exists, so the description must convey return value, which it does by enumerating the link types returned. Combined with the safety guarantee, an agent has enough to call and interpret it, though auth/permission context is absent.

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?

There is a single optional parameter with 100% schema description coverage, so the schema already defines it. The description's 'one product instead of the cart' adds a small amount of framing about the alternative scope but little beyond the schema, 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 verb-and-resource: it returns the link(s) where a person completes purchase for the current cart or one product. It clearly distinguishes itself from siblings like cart and product by noting it is a human handoff and that 'this server never places an order or takes a payment.'

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 implied by 'for this session's cart (or one product),' which tells the agent the scope. However, it never explicitly says when to prefer this over cart, product, or store, nor does it name any exclusion, so routing guidance remains inferential.

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