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

Annotations only declare the safety profile (readOnly, non-destructive, openWorld=false); the description adds what actually happens: a 0.05% one-time fee taken inside the transaction, interest accruing as funds are borrowed, simulation from the wallet, and an explicit 'Nothing is sent.' That is real behavioral disclosure beyond the structured fields, and 'Nothing is sent' is fully consistent with readOnlyHint=true.

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 compact sentences, purpose front-loaded, then mechanics (fee, interest), then return shape and the no-broadcast guarantee. The parentheticals carry load rather than padding; nothing is wasteful.

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, the description correctly compensates by describing the return shape (ordered unsigned transactions, optional EIP-5792 batch, sign_url, simulation). It omits whether a token approval/allowance must already exist and whether the wallet needs a prior USDC balance, which an agent might need to reason about before calling.

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 both parameters (wallet, amount_usdc) are already documented with format rules and the 'at least 1' minimum. The description adds only the fee context, not parameter-level semantics, so the baseline 3 applies.

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 precise verb (lend), asset (USDC), and venue (Morpho WETH/USDC market), which is enough to separate it from build_lend_withdraw and build_borrow without opening any schema. The market-level specificity is more informative than a generic 'lend USDC' phrasing would be.

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 context for when this applies (supplying into the Morpho WETH/USDC market) but never names an alternative such as build_lend_withdraw for exiting a position, nor states any precondition the agent should check first. Usage is implied by the tool name and description rather than explicitly guided.

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