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

Beyond the annotations (readOnlyHint=false, idempotentHint=false), the description adds a valuable behavioral trait: 'Checkout creation is not payment proof,' which corrects a likely assumption that preparing checkout equals receiving payment. It also emphasizes the human-confirmation prerequisite. It doesn't discuss idempotency or side-effect details, but the added caveat is meaningful.

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 sentences with no filler: the first front-loads the action and precondition, the second adds a crucial caveat. Every clause earns its place, and the structure supports quick scanning.

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?

Covers the key precondition and the non-payment caveat, which are core to correct usage. But with no output schema and a short description, the agent has no idea what the tool returns (e.g., checkout URL, ID) or what happens after checkout creation. This is a clear gap for a tool that creates a resource.

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 0%, and the description mentions none of the 8 parameters. The description does not compensate for the schema's silence, leaving the agent to infer semantics purely from parameter names like user_confirmed_payment and service_plan. Some names are self-explanatory, but the description itself adds no parameter-level meaning.

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?

States a specific verb and resource ('prepare the secure checkout'), names the triggering precondition ('human explicitly agrees to pay'), and adds a differentiating caveat ('checkout creation is not payment proof'). The sibling tools are get_* operations on offers and order status, so this action-oriented prepare tool is clearly distinct without needing to open the schema.

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?

Provides an explicit trigger condition ('After the human explicitly agrees to pay for a selected website service'), which tells the agent exactly when to call. However, it does not name sibling tools or state when-not-to-use, so it captures the 'clear context' level but not the full 'explicit when/when-not/alternatives' level.

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