Open checkout (payment is human-only)

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

Beyond annotations (openWorldHint: true, readOnlyHint: false), the description adds critical behavioral details: 'The tab is left open in the user's browser' and 'This tool NEVER clicks the pay button — the final payment is always done by the human.' No contradictions with annotations.

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 three sentences, each serving a purpose: action, constraint, usage pattern. It is front-loaded with the core action and contains no redundant information.

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 simple tool with one parameter and no output schema, the description explains the outcome (order sheet opened, tab left open) and the two-step process. It could mention error conditions (e.g., empty cart), but completeness is high given low complexity.

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 100% with a good description of the 'confirm' parameter. The description reiterates the two-step pattern but adds no new semantic information beyond the schema. 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's purpose: 'Open the order sheet (pre-payment page) from the cart and STOP.' It uses a specific verb ('Open') and resource ('order sheet'), and distinguishes itself from all sibling tools as the only one dealing with checkout.

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 usage guidance: call without 'confirm' to preview the cart, then with 'confirm=true' to open the order sheet. It also states the tool NEVER clicks the pay button, clarifying when the human must act. It does not explicitly list when NOT to use it, but the sibling list contains no other checkout tool, so the guidance is clear.

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