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

Annotations only say readOnly=false and destructive=false, so the description carries the real burden here and does so well: it discloses that checkout charges nothing until the user pays, and that change previews the current charge before applying with confirm. This is exactly the kind of irreversibility/confirmation behavior the annotations omit. It stops short of describing failure modes or what happens to an existing subscription mid-cycle.

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?

A single dense sentence per action with the default called out first and no filler or restatement of the name. It is slightly run-on; the action list could be broken into bullets for faster scanning, but nothing is wasted.

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 four parameters, no output schema, and a mutating action, the description covers the full lifecycle: read the plan and next charge, get a link, or preview-then-commit a change. The absence of an output schema is offset by describing what overview and change return. Minor gaps remain on error handling and proration behavior.

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 only 50% (org and confirm are documented; action and plan are bare), and the description compensates by explaining each action's meaning and the allowed plan values pro|scale. The confirm workflow (set true only after the preview was returned without it) is understood end-to-end. It does not add format detail beyond enum values.

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 the resource (the organization's plan and billing) and enumerates the three concrete operations the tool performs, each with a quoted action name. An agent can distinguish overview / checkout / change from each other and from unrelated siblings without opening the schema.

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?

It clearly conditions each action: overview is the default, checkout is for obtaining a payment link, and change is explicitly for an organization that is already paying. The checkout-vs-change split is the key routing decision and it is spelled out. There is no explicit when-not guidance or reference to a sibling tool for adjacent billing questions.

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