auto_pay_checkout

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

No annotations are provided, so the description carries full transparency burden. It discloses the auto-detection behavior and preconditions, but does not mention side effects like card charging, failure outcomes, or potential human approval triggers. Given the critical financial nature of the tool, this is a moderate gap.

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 two sentences with a front-loaded mandatory warning, making it highly scannable. Every sentence contributes critical information (SOP requirement, usage condition, alternative step) without fluff.

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?

The description covers key prerequisites, usage constraints, and an alternative for physical goods. It doesn't describe post-payment behavior or response format, but the simple 2-parameter schema and lack of output schema make this less critical. Overall, it is reasonably complete for a high-stakes action.

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 description coverage is 100%, with both parameters (checkout_url and card_alias) well-described in the schema itself. The description adds no additional parameter detail, but the schema already provides sufficient semantic meaning, so a baseline of 3 is appropriate.

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 'Auto-detects Web3 or Fiat and completes payment' on payment pages, which is a specific verb and resource. It also includes a conditional ('Only use on PAYMENT pages where final total is visible'), but it doesn't explicitly distinguish itself from the sibling tool 'execute_payment', though the auto-detection detail provides some differentiation.

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 explicit when-to-use context: 'Only use on PAYMENT pages where final total is visible' and a mandatory prerequisite 'Read mcp://resources/sop first'. It also names an alternative for physical goods ('get_merchant_hints first'), giving clear guidance on when to use this tool versus others.

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