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

Annotations only declare openWorldHint=true, so the description carries most of the burden and does disclose meaningful behavior: all actions require authentication, Stripe-hosted URLs are forwarded to a human, and setup intents are 3DS-safe. It omits destruction/reversibility details for mutations like remove-payment-method or set-default-payment-method, and gives no idempotency or rate-limit context.

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 purpose, then lists actions and paths in a scannable structure. Slightly uneven — workflow-heavy actions get explanatory clauses while overview, payment-methods, billing-info, and invoices are bare names — but overall efficient with little waste.

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 13-action, 18-parameter tool with no output schema and minimal annotations, the description is reasonably complete: it enumerates actions, gives workflow paths, and notes auth. It doesn't clarify return shapes or error behavior for read actions (overview, invoices, invoice-detail), leaving some gaps given no output schema exists.

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 description coverage is 100% with per-parameter action mapping (e.g., 'for update-billing-info', 'required for create-payment-link with purpose=subscribe'), so the schema already does the heavy lifting. The description adds only the cross-action workflow context, not per-parameter semantics beyond what the schema provides, so baseline 3 applies.

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 clear verb+resource ('Manage billing for the authenticated user') and enumerates the 13 concrete actions it supports, so the agent knows exactly what surface it covers. It's distinguishable from siblings like agent-wallet and agent-subscriptions by scope, though it doesn't explicitly call out those boundaries.

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?

Provides explicit routing guidance via three named payment paths (Headless: stripe-config → tokenize → payment_method_id; Human-assisted: create-payment-link → forward URL → poll confirm-checkout; SetupIntent: create-setup-intent → confirm → reuse), which is strong when-to-use signal. It stops short of naming when NOT to use this tool or how it relates to sibling tools. Minor inconsistency: 'confirm-checkout' is referenced as a step but is absent from the action list.

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