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

Beyond the annotations, the description discloses key behavioral details: return values (checkout_url, stripe_session_id, amount_due), the user-driven payment workflow (agent must not pay), server-side price fixing, and idempotency via client_request_id. This adds significant context that annotations alone do not provide, without contradicting them.

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 concise (three sentences), front-loaded with the primary purpose, and every sentence provides necessary information: purpose, return values, usage instructions, and idempotency guidance. No wasted words.

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?

Given that an output schema exists and annotations cover safety, the description is complete for an agent to select and invoke the tool correctly. It explains the payment flow, idempotency, and the agent's role, covering all necessary operational details for a checkout tool.

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 100% (both parameters have descriptions). The description adds extra semantic value by explaining that client_request_id ensures idempotency and that package prices are fixed server-side, which implies package determines the amount. This goes beyond the schema's basic 'Offer id from list_offers' and 'Stable id you generate.'

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 clearly states the tool's function: 'Create a Stripe Checkout for a package's 50% deposit.' It specifies the verb ('Create'), resource ('Stripe Checkout'), and scope ('for a package's 50% deposit'), and lists return values. This distinguishes it from sibling tools like create_upload_url or get_inquiry_status.

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 provides clear usage context: it instructs to show the amount to the user and open checkout_url for them to pay, and explicitly notes that agents never complete payment themselves. It also advises passing a stable client_request_id for idempotency. It does not explicitly mention alternative tools or when not to use it, but the context is sufficient for distinguishing from siblings.

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