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

Goes well beyond the annotations by explaining why readOnlyHint is false (each call is charged), disclosing pricing ($0.005/call, first 25 free, failed calls free), auth paths (x402 USDC or card key), and the nonce caveat for EOAs (outgoing txs only). This is genuinely useful behavioral context not present in structured fields.

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 resource and return fields, then pricing and caveats. Dense but mostly earned; the middle section is a long run-on sentence stacking many clauses, which slightly hurts scanability.

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 and no annotation coverage of pricing/account-type semantics, the description carries that burden and does so: it enumerates the returned fields, the account-type classifications, nonce semantics, and cost model. Nothing essential for correct invocation 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 both params are already documented. The description nonetheless adds value by enumerating the default tokens checked (USDC, WETH, cbBTC, DAI, USDbC, cbETH, AERO, EURC) and reinforcing the 20-token cap for the `tokens` param.

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: a live snapshot of an address on Base covering ETH balance, major token balances, up to 20 extra tokens, account nonce, and account type (EOA/contract/EIP-7702). The scope is concrete, but it never names the sibling primitives (base_balance, base_nonce, base_is_contract, base_token_balance) it aggregates, so an agent must infer the differentiation itself.

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 an explicit use case ('Use to check a counterparty's holdings') and a negative scope ('not full transaction, token-transfer or trading history'). It does not, however, name an alternative tool or state when a granular sibling would be preferable to this aggregate.

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