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

Annotations already declare readOnly/idempotent/non-destructive, and the description reinforces this with 'Creates no order and takes no payment,' removing any doubt about side effects. It also discloses what the response contains (AUD price, USDC amount for x402, per-rail notes), which the annotations alone would 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?

A single dense sentence that front-loads the core action and the tier list before the clarifying side-effect note. Nothing is padded, though the rail parenthetical is slightly at odds with the enum set.

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 simple read-only quote tool with no output schema, the description usefully previews the returned fields (AUD price, USDC amount, rail notes) and rules out order creation. It is essentially complete, with only the rail-name/enum mismatch as a minor gap.

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 0%, but both parameters are enums whose values are largely self-describing. The description restates the tier values but names only three payment rails (card, x402 USDC, on-chain bitcoin) against four enum values (stripe, x402, lightning, btcpay), leaving lightning unmapped, so it only partially compensates for the coverage gap.

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 states a specific verb (quote the price) and resource (one tier) and enumerates the valid tier values, so an agent knows exactly what it returns. It also explicitly contrasts with the purchase path ('Creates no order and takes no payment'), separating it from the sibling kit_buy_x402.

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 clause 'Creates no order and takes no payment' tells the agent this is the pre-purchase, read-only lookup and implicitly routes actual purchasing to kit_buy_x402. It gives clear context but never names the alternative tool or states an explicit when-to-use trigger.

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