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

No annotations, so description carries the burden. It discloses the key chaining behavior (returns payment_token required for completion), which is valuable. However, it omits permission/auth needs, failure modes (e.g., expired cart_token), whether it mutates the cart, and rate limits.

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 tight sentences, front-loaded with the action and immediately followed by parameter sourcing and return value. No waste.

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 2-param, no-annotation step in a multi-step flow, the description covers the happy path and the payment_token linkage, and an output schema exists so return values needn't be spelled out. But missing failure modes, mutation semantics, and auth requirements leave notable gaps for a no-annotation 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 0%, so description must compensate. It explains that cart_token comes from add_to_cart and that email is a billing email, adding meaning beyond the bare 'string' type. It does not describe email format/validation or error behavior for invalid tokens.

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?

Clear verb+resource: 'Initiate checkout for a cart.' It explains the outcome (returns a payment_token) which distinguishes it from siblings like confirm_payment. No explicit sibling contrast, but the purpose is unambiguous.

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?

States the prerequisite context ('Provide cart_token from add_to_cart') and that the returned payment_token is needed to complete the purchase, implying confirm_payment follows. No explicit when-not or alternatives, but usage context is clear.

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