open_billing_portal

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

With no annotations, the description carries full burden. It discloses that the tool opens a browser, returns a specific object, and that the user must complete actions in the portal. It also mentions an error condition (400 if no purchase). Good coverage for a simple tool.

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 two sentences with a bullet-like list of use cases. It front-loads the core action and is free of fluff. Slightly could be more organized, but highly efficient.

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?

Given no output schema and no annotations, the description covers purpose, behavior, return value, error condition, and prerequisites. It is complete enough for an agent to use correctly.

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 tool has zero parameters with 100% schema coverage. The description adds no param info (not needed), meeting the baseline expectation for such tools.

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 action 'Open the Stripe Customer Portal' and lists specific use cases like managing subscriptions and updating payment methods. However, it does not explicitly distinguish from sibling tools like get_billing_history, though the use cases imply the difference.

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 use cases ('manage my subscription', etc.) and prerequisites ('requires sign-in AND a prior purchase'). It also states that further steps must be completed in the portal. It does not explicitly list when not to use, but the context is clear.

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