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

Goes well beyond the annotations: discloses malformed addresses return 400 uncharged, exact pricing ($0.01/call via x402 or card key, first 25 free, failed calls free), and that repeats are billed — consistent with idempotentHint=false. It also confirms the call is side-effect free, matching readOnlyHint/destructiveHint.

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?

Front-loaded with the action, scope, and alternative before cost details, so the essential routing information comes first. Slightly redundant on billing ('each call is charged, so repeats are not free' after the price sentence), which costs a bit of tightness in an otherwise dense paragraph.

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 still enumerates returned fields (direction, counterparty, amount, transaction), ordering, and the 50-row cap. Combined with error behavior and pricing, an agent has everything needed to decide, call, and interpret results.

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 already 100%, and the description reinforces the meaningful defaults (USDC default token, 1–2,000 blocks with default 1,000) and supplies a concrete address example. It also adds the result cap ('up to 50') and ordering ('newest first'), which the schema does not express.

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 (List), resource (a wallet's recent ERC-20 transfers), chain (Unichain), scope (in and out, last N blocks), and default token (USDC). It also explicitly separates itself from unichain_token_balance, so an agent can distinguish this from the most confusable sibling without opening either schema.

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?

Gives concrete when-to-use cases ('confirm a payment arrived or see what was sent') and names the alternative for the adjacent need ('for the current balance use unichain_token_balance'). The boundary between this tool and the balance tool is unambiguous.

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