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

Beyond the annotations, the description discloses the exact source, destination, amount, threshold, and safety boundary. This gives a clear picture of the tool's behavior without requiring the agent to infer side effects.

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 cover the action, the amount, the constraint, and the recommended context for use. Every sentence contributes concrete information, and the key behavior is front-loaded.

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?

Given no parameters, sparse annotations, and no output schema, the description still explains when to call, what it does, where funds move, how much, and what it cannot do. Nothing necessary for correct invocation is missing.

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?

This tool has zero parameters, so parameter semantics are largely not applicable. The description helps by making the action fully deterministic and removing any need for a caller to supply additional context.

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 uses a specific verb phrase — 'Move a little USDC from the trading subaccount back to the WALLET' — and clearly identifies the condition and exact reserve amount. It also differentiates itself from siblings like deposit_to_subaccount by making the transfer direction explicit.

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 provides a precise trigger ('when the wallet is at or below $0.55') and an explicit use case ('Use after a transaction fails for lack of gas'). The restriction that it cannot send funds anywhere else makes the limits of use unambiguous.

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