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

Annotations only cover the read-only/open-world safety profile, but the description adds the real behavioral payload: the x402 flow, the first request returning HTTP 402 with payment instructions (amount, network, pay-to address), and the retry with a signed X-PAYMENT header returning a receipt. This is context no structured field provides.

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?

Purpose is front-loaded and every sentence carries information, but the payment-workflow instructions expand the description well beyond a one-line read tool. They earn their place, though the paragraph is longer than needed for pure tool selection.

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?

With no output schema, the description covers what comes back (products, USDC prices, buyUrl) and how to act on it via the x402 handshake. An agent has everything needed to call this and interpret the result 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% and the single handle parameter is already documented with an example format in the schema. The description adds only that the handle identifies the seller whose storefront is read, so the schema does the heavy lifting and a baseline 3 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?

States a specific verb and resource: lists the products a given swop.id sells on their SmartSite, including USDC prices and each product's x402 buyUrl. It explicitly distinguishes itself from the sibling swop_list_my_products, which covers the caller's own catalogue.

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?

Names the alternative (swop_list_my_products) and the condition selecting it, then gives the end-to-end purchase procedure for the returned buyUrl. It also sets an explicit when-not/precondition: get user confirmation on product, price, and seller before paying.

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