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

Annotations already indicate this is not read-only (readOnlyHint=false) and not destructive, but the description adds the critical caveat 'Checkout creation is not payment proof' – a behavioral detail beyond annotations that prevents misuse. It could mention more side effects, but the added caveat provides meaningful transparency.

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 concise sentences, both earning their place: the first states the action and precondition, the second a necessary safety caveat. There is no filler or repetition of schema details, and the key information is front-loaded.

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 mutation tool with no output schema, the description covers the precondition and a key caveat but does not explain what the agent should expect after preparation (e.g., checkout URL, ID, or next steps). It also assumes the agent understands 'selected' without linking to the offers step. This is adequate but leaves notable gaps.

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%, so the description must compensate. It clarifies user_confirmed_payment ('after the human explicitly agrees to pay') and domain ('supplied website'), and 'selected' hints at tier, but it does not explain the tier enum values ('complete' vs 'patch') or the referral_code parameter. This leaves half the parameters semantically under-specified.

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 states a specific action ('prepare') on a clear resource ('secure checkout') for a supplied website, with a precondition ('After the human explicitly agrees to pay'). This distinguishes it from the sibling get_website_audit_offers, which is about offers rather than checkout creation.

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 clearly indicates when to use the tool: only after the human explicitly agrees to pay. It provides this context without explicitly naming alternatives or exclusions, but the precondition is enough to guide correct usage. It stops short of a full when-not/alternative statement, so it earns a 4.

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