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

With no output schema, the description usefully discloses the return shape and the live-contract read, plus a genuinely non-obvious behavioral trait: a $0.001 USDC per-successful-call fee via x402, which affects how an agent should budget calls. It does not explain rate limits or failure/prerequisite behavior, so it falls short of full transparency.

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?

Three sentences, each with a distinct job: what it returns, when to call it, what it costs. The scoping detail (on Base) is front-loaded before the usage hint, and 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?

For a two-parameter read tool with no output schema, the description covers the chain scope, the return fields, the cost mechanism, and the intended use case. An agent has everything needed to select and invoke it correctly.

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 description coverage is 100%, so both parameters (token, address) are already documented as 0x addresses. The description adds no clarification over the schema, e.g. that `token` must be the contract address rather than a symbol, which is the most common misuse. Baseline 3 applies when the schema does the heavy lifting.

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?

Specific verb+resource (ERC-20 token balance of a wallet) scoped to the Base chain, and it enumerates what is returned (raw amount, decimals, symbol, human-readable amount). The chain qualifier cleanly separates it from the many sibling *token_balance tools (eth_, arb_, op_, polygon_).

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 to check stablecoin or token holdings before a transfer, payment or trade" gives a clear triggering context. It stops short of naming alternatives (e.g. use eth_token_balance for Ethereum, or base_token_info for metadata), so there is no explicit routing or when-not guidance.

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