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

Annotations already declare readOnlyHint=true, destructiveHint=false, idempotentHint=false and openWorldHint=true, and the description reinforces this ('reads or computes only and changes nothing') while explaining why repeats are not free, which accounts for the idempotent hint. It adds cost/permission context ($0.005/call via x402 USDC or card key, first 25 free, failed calls free) and the account-type determination. However, it says nothing about the shape or completeness of the returned token list (e.g. missing balances, decimals, or partial-failure behavior on extra token addresses).

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?

The chain scope and sibling routing are front-loaded in the first clause, and every subsequent sentence carries operational information (coverage, nonce meaning, pricing). It is dense with parentheticals and semicolons, which makes it slightly harder to parse than it needs to be, but there is no filler.

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 only two fully documented parameters, an existing annotation set, and no output schema, the description covers everything an agent needs to call correctly: chain restriction, default coverage, extra-token cap, nonce semantics, account-type output, and cost/access model. Nothing material is missing for a read-only snapshot 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; the description nevertheless adds meaning by listing the default token set (USDC, WETH, cbBTC, DAI, USDbC, cbETH, AERO, EURC) versus the user-supplied 'tokens' addresses, so an agent knows the extra addresses are additive rather than a replacement. It also supplies a concrete example address and confirms the address must be on Base. It does not state what happens if a passed token address is invalid or non-ERC-20.

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 concrete verb-set and resource (ETH/token balances, account nonce, account type) scoped to Base, and explicitly distinguishes itself from wallet_balances (all chains) and wallet_portfolio (USD values). An agent can tell it apart from the per-chain base_balance/base_nonce siblings because it bundles balances, nonce, and EOA/contract/EIP-7702 classification.

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?

Opens with the exclusions and the alternatives that cover them ('Base only (all 5 chains: wallet_balances; USD values: wallet_portfolio)'), then names the intended use case ('check a counterparty's holdings'). It also bounds expectations: the nonce is not transfer or trading history.

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