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

The description discloses the key side effect ('Deducts from account balance'), the two-phase behavior ('Stage renewal' vs. final execution), and the return signal (actionId requiring confirmation). These traits go well beyond the annotations, which only state readOnly/idempotent/destructive are false, leaving the actual behavioral contract unexplained.

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 sentences, each earning its place: purpose/scope, side effect, and return-handling instruction. Front-loaded with the action and resource, and no filler or repetition of schema details.

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 staged mutation with no output schema, the description provides everything needed to call and complete the action: it states the side effect, identifies the return value (actionId), and instructs the follow-up call. It appropriately leaves parameter format and authentication to the schema.

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 input schema already contains 100% coverage with clear descriptions for domain, years, and sessionKey, so the description need not restate them. It adds minimal semantic nuance by linking 'specified number of years' to the years parameter, but does not deepen understanding of the parameters beyond the schema.

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 starts with a specific verb-resource pair ('Stage renewal of a domain') and specifies the key parameter (number of years). It clearly distinguishes this from related siblings by framing it as a staged renewal that deducts from account balance, rather than a toggle like updateDomainAutoRenew or a transfer/registration action.

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 an explicit usage flow: present the returned summary to the user and call executeConfirmedAction if they approve. This tells the agent exactly how to handle the tool's output and when to involve the user. However, it does not name or exclude alternatives like updateDomainAutoRenew, so some inference is left to the agent.

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