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

With no annotations, the description carries the burden and does well: it names the supported chains, caps token lookups at ten, and discloses the paid x402 model (0.005 USDC per call on Base) — a material behavioral trait agents rarely get. It omits failure behavior for unsupported chains or malformed token addresses, and doesn't explicitly state the operation is read-only.

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 sentences, capability first, selection guidance second, pricing last. Nothing is redundant with the schema; every clause adds information.

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?

No output schema exists, and the description compensates by enumerating what comes back (balance, nonce, token amounts with symbol and decimals). The free-form 'tokens' parameter format and the omitted-chain default are the only remaining gaps for a 3-param tool.

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 baseline is 3, but the description adds real semantics: which chains the 'chain' param accepts (Base, Polygon, Arbitrum) and that the 'tokens' param takes up to ten ERC20 addresses with symbol/decimals returned. Only the default chain behavior when 'chain' is omitted remains unaddressed.

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 (portfolio snapshot for a wallet) plus exact contents: native balance, nonce, and up to ten ERC20 token balances with symbol and decimals. The 'one call / instead of many calls' framing distinguishes it from siblings evm_balance, evm_nonce, and evm_token_balance.

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?

'Use it when an agent needs a full wallet snapshot instead of many calls' gives a clear selection rule and implicitly routes away from the single-purpose siblings. It stops short of naming an explicit exclusion (e.g. use evm_token_balance when you need only one token) or stating what to do for unsupported chains.

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