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

Despite readOnlyHint being present, the description adds meaningful behavioral detail: wallet balance is NOT collateral until deposited, there is a $0.95 gas reserve, and funding synthesizes the deposit decision. This goes well beyond the annotation and prevents a common misunderstanding.

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: the first names the resources being fetched, the second clarifies the collateral versus wallet distinction, and the third explains the summary field and next actions. Information is front-loaded and nothing is redundant.

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 parameterless read-only tool with no output schema, the description is complete. It explains both key balances, the gas reserve, the suggestedAction logic, and even references the relevant sibling tools deposit_to_subaccount and top_up_gas.

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?

There are no parameters and schema description coverage is 100%, so there are no input ambiguities. The description instead explains the meaning behind the returned balances, which is the only semantic value needed here.

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 and identifies two distinct resources: the subaccount collateral balance and the on-chain wallet bank balance. It also disambiguates these two concepts clearly, which helps an agent understand what this tool reports and what it does not.

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 clear context about when the balances matter and explains the suggestedAction field, including conditions for depositing spare USDC or topping up gas. It does not explicitly provide exclusionary routing against sibling balance tools, so it stops slightly short of a full 5.

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