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

With no annotations, the description carries full disclosure burden. It helpfully states the tool is idempotent and depends on prior approval, but omits what capture actually does to the order (charges the payer), what happens on failure/expired approval, and any permission requirements.

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 terse sentences with no filler, front-loading the precondition. The brevity is efficient, though it borders on under-specification for a payment-capture tool.

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 1-parameter tool with no output schema and no annotations, the description covers the precondition and idempotency but says nothing about the result of a capture or error behavior, leaving an agent to guess the response semantics.

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?

The single parameter order_id has 0% schema description coverage, and the description never mentions it or its expected format (e.g., the PayPal order ID returned at creation). The precondition hints at the approval flow but adds no meaning about the argument itself.

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 name and title make it clear this captures a PayPal payment, but the description body never states the action itself -- it only gives a precondition ('Call after the payer approved payment.approve_url'). Purpose is inferable from the name, not from the description, and there is no differentiation from siblings like create_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?

'Call after the payer approved payment.approve_url' is a clear, actionable precondition for when to invoke the tool, and it references the specific field the agent must have seen. It stops short of naming alternatives or when-not-to-call cases, so it is not a 5.

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