Preview Order

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, and the description reinforces this with 'Non-binding and safe' and 'WITHOUT placing it'. It adds new behavioral context by specifying the return values (estimated cost, transaction fee, buying-power comparison), which the schema and annotations do not convey.

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 three sentences, with the core purpose front-loaded. Every sentence contributes value: what it does, what it returns, and when to use it.

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 tool is simple, the schema is thorough, and the description covers purpose, safety, return info, and usage guidance. With annotations handling the safety profile, no critical gaps remain.

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?

Input schema describes all 5 parameters with 100% coverage. The description does not elaborate on parameter usage, but the schema already provides default values and constraints, so the baseline of 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?

The description immediately identifies the tool as a validation/preview action ('price and validate an order WITHOUT placing it'), using a specific verb and resource. It clearly distinguishes from sibling draft_order by emphasizing no order is placed.

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?

Explicitly instructs to 'Use this before draft_order to check affordability and fees', naming the alternative and providing a concrete use case. This exceeds a simple when-to-use statement.

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