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

Beyond the annotations, the description adds valuable behavioral context: the session is short-lived, the customer must explicitly approve, and the operation has no charging or extraction-provider side effects. This meaningfully reduces ambiguity for a tool that could otherwise be confused with a purchase/checkout flow.

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 action and consent condition are front-loaded, and the second sentence adds only the side-effect exclusions that genuinely matter for correct selection. Every clause earns its place.

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 single-boolean tool with annotations and 100% schema coverage, the description covers when to use it, consent requirements, and important non-effects. The only minor gap is not describing what the tool returns, such as a portal URL, but with no output schema and a simple operation this is a minor omission.

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?

The only parameter, confirmCreate, is fully documented in the schema with a const true constraint and a clear description. The tool description's consent condition mirrors the schema's confirmation requirement rather than adding new parameter-level semantics, so the baseline score 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 names a specific action and resource: 'Open a short-lived Stripe Billing Portal.' It clearly scopes the tool to explicit customer requests to manage payment methods, invoices, or the AgentMart subscription, and distinguishes it from purchase/execution flows by stating it does not charge or call an extraction provider.

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 gives a clear, explicit trigger condition: only use when the authenticated customer explicitly asks to manage billing items. It also states exclusions ('does not charge... or call an extraction provider'), which routes non-billing-management requests elsewhere, though it does not explicitly name the alternative sibling tool.

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