Preview checkout

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

With no annotations provided, the description carries the full transparency burden. It reveals the most important side effect boundary ('This does not place an order') and notes the quote is short-lived and uses live data. However, it does not explain whether the quote is saved, whether the operation modifies the cart, or what prerequisites are required (e.g., existing items). For a non-destructive preview tool, this is adequate but not thorough.

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 two concise sentences with no filler. It front-loads the core purpose and immediately includes the key limitation ('does not place an order'). Every word contributes to understanding the tool's role.

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?

The definition is fairly complete for a simple one-parameter tool, but it lacks an output schema and does not describe what the returned quote contains, nor does it state whether a cart or items must exist before calling. Since the only parameter is well-documented in the schema, the main gaps are output format and usage prerequisites, making the description somewhat incomplete for confident 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?

The schema description coverage is 100%: the only parameter, shipping_address, is fully described ('Optional address used to calculate the checkout quote'). The tool description itself makes no mention of parameters, so it adds no semantic value beyond the schema. Baseline 3 applies because the schema already handles the meaning.

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?

Description clearly specifies the action ('create a short-lived checkout quote') using live eBay prices, and explicitly states what it does not do ('This does not place an order'). This disambiguates it from the sibling tool place_order, giving an agent a precise understanding of the tool's purpose.

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 clear usage context: this tool is for previewing checkout with live prices, not for finalizing orders. It does not explicitly name the alternative tool (place_order) or specify prerequisites like 'items must be in the cart', but the 'does not place an order' statement provides a key exclusion that helps route an agent.

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