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

Annotations only declare the safety profile (not read-only, not open-world, non-destructive). The description adds substantial behavioral context the annotations cannot: prices in the request are rejected, shipping is auto-charged for physical goods, card rail only applies when card-enabled and all items physical, response shape (cardOffered:true, paymentRequest null until rail selection), the exact endpoints for card/crypto selection, and that settlement is automatic with no confirmation needed.

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-loaded with the core action and the alternative before diving into rails and response details. It is dense and long, but nearly every clause carries operational weight (required fields, rejection conditions, endpoints, polling). Slightly heavy for a single block of prose.

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 complex 7-param mutation tool with no output schema, the description compensates by describing the return values (paymentRequest solana: URL, cardOffered flag), the rail-selection flow, and the settlement/polling model with swop_get_checkout. An agent has everything needed to invoke and follow up 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 coverage is 100% so the baseline is 3, but the description adds real meaning beyond the schema: prices must NOT be sent (a request price is rejected), buyer fields are hard-required for physical items, and offerCard only takes effect under specific conditions. Minor gap: it doesn't clarify selectedOptions or buyerPhone behavior beyond what the schema states.

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 ('creates a checkout for a cart') and pins the scope ('the linked account's OWN products'), so the agent immediately knows this is a seller-side checkout rather than a link generator. It explicitly names the sibling it is not (swop_get_product_link) for the single-shareable-link case.

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?

Gives explicit when-to-use ('take payment on the seller's own website... instead of being sent to Swop') and when-not ('For a single shareable link use swop_get_product_link instead'). It also lays out prerequisites: buyer name/email/address are required for physical items and the call is refused otherwise.

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