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

With no annotations, the description carries the burden, and it does disclose the key mechanism: the buyer pays on the merchant-hosted page and Qomvia never handles payment for goods. However it is silent on whether completing a session is idempotent, whether the session becomes unusable afterward, and what errors occur for expired/invalid sessions.

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 its result, with the payment-liability clarification following immediately. No filler or repetition of the tool name.

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 single-parameter tool with no output schema, the description usefully explains what the caller receives (a payment URL) and where payment occurs. It is slightly thin on post-completion session state and failure modes, but otherwise adequate.

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?

Only one parameter exists and schema coverage is 100%, so the schema already documents sessionId fully. The description adds no format, sourcing, or lifecycle detail about the session id, making this a baseline 3.

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+resource ('Complete a checkout session') and names the concrete outcome ('receive the merchant-hosted payment URL'), which cleanly distinguishes it from create_checkout_session, cancel_checkout_session, and get_checkout_session siblings.

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?

Usage is implied by the state-transition verb - an agent infers this is called after a session exists - but there is no explicit when/when-not guidance, no mention of required session state, and no routing advice relative to get_checkout_session or cancel_checkout_session.

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