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

Rich disclosure beyond the annotations: the tool returns unsigned transactions in signing order (also as a single EIP-5792 batch), simulated from the wallet, plus a sign_url for a human owner, and 'Nothing is sent'. This explicitly operationalizes the readOnlyHint=true on what would otherwise read as a transaction-building tool, with no contradiction.

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?

Two tight sentences, front-loaded with the action and its constraint, then the return/safety contract. No filler, no repetition of the title, and each clause carries information an agent needs.

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?

With no output schema present, the description does the work of describing the return shape (ordered unsigned txs, batch form, sign_url) and the simulation/no-send guarantee. It leaves unaddressed items like token approval prerequisites or gas handling, but the essential contract for calling and reasoning about the result is present.

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 coverage is 100%, so the baseline is 3, but the description adds a real constraint the schema omits: the amount must be at least $1 and the top-up occurs 'in its current range'. That is meaningful semantic value on top of the already-documented parameters.

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?

States a specific verb+resource: adding USDC to an existing position, scoped to its current range. The word 'existing' and 'Add to' distinguish it from build_vault_deposit and build_vault_withdraw, but no sibling is named explicitly, so the routing is inferred rather than stated.

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 implies when to use it (topping up an existing position rather than opening a new one) but never names an alternative or states a when-not condition. The '$1 minimum' and 'current range' constraints give some usage context but the agent must infer the boundary against build_vault_deposit.

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