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

Beyond the annotations, the description discloses critical behavior: the quote is UNPAID, the tool 'never signs or pays,' it requires a locally generated private capability, and both the quote and idempotency key must be persisted first. This adds real behavioral context that annotations alone do not provide. No contradiction with the annotations.

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?

Three short sentences, each earning its place. The main purpose is front-loaded, and the constraints and non-behavior are stated without unnecessary wording.

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 covers prerequisites, auth, persistence, and the critical exclusion of signing/paying. It is not perfect only because there is no output schema and the description does not describe the return value, and the pronoun 'it' in 'Persist it' is slightly ambiguous.

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 schema documents amount and maxAmountUSD as USDC decimal strings, but the description adds meaning by mapping maxAmountUSD to 'budget' and ownerAuthorized to 'owner permission.' It also stresses the idempotencyKey's role by saying to persist it first. This meaningfully compensates for the 50% schema description coverage.

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 states a specific action and resource: 'Reserve an UNPAID optional tip quote.' This clearly differentiates it from the read-only sibling tools get_tip_receipt and get_tip_terms, since this tool creates/reserves rather than retrieves.

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 gives clear conditions for use: 'only with owner permission and budget,' requires a private capability in the Authorization header, and tells the agent to persist the idempotency key first. It does not explicitly name alternatives or say when not to use it, but the constraints are strong and actionable.

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