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

Goes beyond the annotations by disclosing the 30-minute price lock, the exact outputs (quote_id, current price, customer-confirmation requirements), and the absence of side effects. The readOnlyHint/idempotentHint annotations already cover the safety profile, and the description reinforces rather than contradicts them; it could still say what happens when the quote expires.

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?

Two sentences, front-loaded with the action and artifact, followed by outputs, the 30-minute lock, the no-side-effect guarantee, and next steps. No filler.

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 usefully enumerates the return values and the follow-on tools, and it clarifies the non-mutating nature of the call. The only real gap is the undocumented destination parameter.

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 only 33%: lang is documented in the schema, but plan_id and destination have no schema descriptions. The description compensates for plan_id by naming the tools that produce it, yet destination is left entirely unexplained in both places.

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 artifact: 'Prepare a time-limited signed quote' for a plan_id. It also ties the resource to how it's obtained (search_plans or get_plan), which cleanly separates it from purchase, create_checkout, and get_order.

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 names the prerequisite lookup tools and the two downstream alternatives, with the condition selecting each ('create_checkout for customer-paid Stripe Checkout or purchase for an enabled alternate method'). It also states the negative case: no order, payment, or eSIM is created.

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