buy_checkout

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

No annotations exist, so description carries full burden. It discloses that the tool is policy-enforced and may return specific statuses with machine-readable reason chains, indicating behavior beyond a simple purchase. This adds value without contradicting any annotation.

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?

Description is a single clear sentence followed by a brief Sentinel note. It is front-loaded and efficient, though it could be structured with bullet points for parameter details.

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 8 parameters, no output schema, and no parameter explanations in description, the description is incomplete. It doesn't mention expected return values (e.g., order confirmation) or error handling beyond the Sentinel statuses. More context is needed for an agent to use it effectively.

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 only 38% (low), and the description fails to explain any parameters beyond the Sentinel note. Parameters like merchant, tip_cents, delivery_time are not described, leaving the agent without context on their usage or format.

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?

Description states 'Place and pay for the current cart at a linked merchant', clearly identifying the action (place and pay), object (cart), and target (linked merchant). Distinguishes from sibling tools like buy_add_to_cart and buy_view_cart.

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?

Describes Sentinel policy enforcement and possible returned statuses (denied_by_sentinel, approval_required_by_sentinel), giving context on when the tool may not succeed. However, lacks explicit guidance on when to use vs. alternatives like buy_add_to_cart or when to check cart status first.

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