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

Goes well past the annotations by clarifying that nothing is charged at creation time, that payment happens on the hosted page, the refund policy, and a launch-gating error code ('checkout_not_open'). It is consistent with readOnlyHint=false, idempotentHint=false and destructiveHint=false, and adds facts an agent could not derive from structured fields.

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?

Front-loads the action and the critical 'does NOT charge' clarification before the pricing block. The price and refund sentences are somewhat list-like but each carries decision-relevant information for a purchasing agent.

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 no output schema, the description usefully discloses the return shape (URL or 'checkout_not_open') and the payment handoff, which is the key behavioral risk for this mutation tool. Only minor gaps remain, such as behavior on invalid or unlaunched product ids beyond the single error string.

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 67%, with email and agent_name already described in the schema; the description adds pricing context for a few product tiers but never maps prices to the 23-value product_id enum, so most enum members remain self-descriptive only. Baseline 3 is appropriate given the schema does most of the work.

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 ('Create a Stripe-hosted checkout for one Agent Field Kit product') and names the return value (its URL). It does not explicitly differentiate itself from the nearby request_kit or get_product siblings, so the agent must infer that this is the paid path versus a free kit request.

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?

Usage is implied by the transactional language and the embedded gate ('a human, or an agent with explicit payment authority, must pay on the returned page'), which is genuinely useful guidance about who can complete the flow. However, there is no explicit when-to-use-this vs. request_kit/get_product routing or any stated preconditions beyond payment authority.

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