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

Beyond the annotations (readOnlyHint=false, idempotentHint=false), the description discloses that the action deducts from the account balance, requires authentication, and returns an actionId that must be passed to executeConfirmedAction for approval. This gives the agent essential behavioral context about cost, authentication, and the two-step confirmation flow that annotations alone do not provide.

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 compact and front-loaded with the core action, then the key alternative, then the side effects and follow-up step. Every sentence contributes necessary information without repetition or filler.

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?

There is no output schema, so the description correctly explains the return value (actionId) and the next action required. It also covers prerequisites, the triggering condition, cost, authentication, and the alternative tool. An agent has enough context to call it correctly and complete the confirmation flow.

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%, so the schema fully documents all three parameters. The description adds minor context by implying authCode is the code obtained from the losing registrar, but it does not materially expand on the schemas for domain or sessionKey. Baseline 3 is appropriate given the high schema 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 verb and resource: 'Starts a transfer for a domain already prepared at the losing registrar.' It also explicitly differentiates itself from the sibling transferDomain, which handles staging transfer plus registrant assignment in one step. This disambiguation is strong and immediately actionable.

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 explicit when-to-use guidance: use this tool only when the domain is already unlocked and the auth code is in hand. It names the alternative transferDomain and specifies the condition for choosing it ('when the user gives you contact details'). It also explains the required follow-up step with executeConfirmedAction, leaving no ambiguity about the workflow.

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