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

With no annotations, the description carries the full burden of behavioral disclosure. It does well: states the agent never handles card details (security), the buyer opens the payment URL, the QR is emailed, and charges are in USD. It does not disclose potential side effects like charge failures or rate limits, but covers the key behaviors an agent needs to know.

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?

Every sentence in the description earns its place. It starts with the core action, explains return values, gives the follow-up step, and notes the mandatory email. No redundant or filler content. The structure is logical and flows well.

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?

The description is complete for a tool with no output schema: it explains return values, the post-payment flow, the email requirement, and the currency. It doesn't mention error handling or how to obtain the sku, but those are covered by sibling tools and the schema. Given the tool's complexity, this is adequate.

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%, so the schema already documents all parameters. The description adds some usage context (e.g., stressing the email must be real, mentioning currency), but it does not introduce new semantic meaning beyond the schema. The baseline of 3 is appropriate since the schema does the heavy lifting.

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: 'Create a secure Stripe payment link for an Alt eSIM plan.' It specifies the resource (eSIM plan), the action (create payment link), and the return values (payment URL and checkout_session_id). It also distinguishes itself from siblings by describing the follow-up with get_qr_code, which is a unique workflow.

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 clear when-to-use context: it's for creating a payment link when a buyer wants to purchase a plan. It gives a sequenced instruction ('After the buyer pays, call get_qr_code') and a mandatory requirement ('You MUST collect the buyer's real email'). It does not explicitly list alternatives or when-not-to-use, but the flow is clear enough for an agent.

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