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

With no annotations, the description carries full burden. It discloses that the call does not fund the order, that escrow is per-order, that status changes automatically upon funds detection, and that shipping is conditional. It does not mention any destructive side effects or permissions, but for this tool the disclosed behavior is substantial and non-obvious.

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?

The description is front-loaded with the main action and the funding requirement. It is a single paragraph with a clear IMPORTANT note. It is somewhat lengthy but every sentence adds value; there is no fluff. It could be tightened, but it is well-structured and readable.

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?

Given the tool's complexity (7 parameters, 1 required) and no output schema, the description explains the return values and the funding workflow. It does not explicitly explain how to obtain variantId or deliveryOptionId, but the schema references get_listing, which is sufficient. The critical funding steps are covered, making it complete for 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 coverage is 100% for all 7 parameters, so the schema already documents each one. The description adds context about shippingAddress being required for physical listings, which the schema also states, and reiterates the funding flow, but it does not clarify variantId or deliveryOptionId beyond what the schema says. The description provides marginal value beyond the schema, so 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?

The description starts with a specific verb and resource: 'Places an order against a listing.' It also names the return values (depositAddress and amountNano). It is immediately clear what this tool does and it is easily distinguished from siblings like cancel_order or get_order without needing to open the 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 description gives explicit step-by-step guidance: the order is not funded by this call, exactly amountNano must be sent to depositAddress, and physical listings require shippingAddress. It also explains the automatic transition to AwaitingShipment. This is actionable and removes ambiguity about the follow-up funding step.

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