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

Adds substantial context beyond the annotations: result cap of 50, newest-first ordering, default token, and the crucial clarification that repeats are not free because billing — not state — drives idempotentHint=false. The only gap is that it doesn't say what an empty result or a token with no transfers looks like, but the read-only/non-destructive profile is fully consistent.

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?

Purpose is front-loaded and every clause carries information (scope, ordering, cap, alternative, error path, pricing). It is dense to the point of being a single run-on block, and the pricing/credits tail is longer than most agents need.

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?

There is no output schema, and the description compensates by enumerating the returned fields (direction, counterparty, amount, transaction) and their ordering and cap. Inputs, caveats and cost model are all covered, so nothing needed to invoke it correctly 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?

Schema coverage is 100%, so the baseline is 3; the description earns extra by restating the blocks range (1-2,000, default 1,000), the USDC token default, and giving a concrete checksummed address example. It doesn't clarify ticker-vs-contract resolution edge cases, which stays in the schema.

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 and resource ('List a wallet's recent transfers of one ERC-20 token'), plus chain, direction (in and out), window and result cap. It also names the sibling it is not (arb_token_balance for current balance), so an agent can distinguish it without opening any 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?

Explicit when-to-use cases ('confirm a payment arrived or see what was sent') and an explicit alternative ('for the current balance use arb_token_balance'). It even covers the failure path: malformed addresses are rejected with 400 and uncharged.

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