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

Annotations are present but thin (readOnlyHint=false, openWorldHint=true), and the description adds valuable behavior beyond them: the live-read semantics and the $0.001 USDC x402 cost charged only 'per successful call' – a meaningful billing detail. It omits rate limits and failure/payment-failure behavior, keeping it below a 5.

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 tight sentences: what it returns, when to use it, what it costs. Zero filler and the output fields are front-loaded.

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 one-parameter read tool with no output schema, the description supplies exactly what is missing: the returned fields and the payment requirement. Nothing an agent needs to invoke it correctly is absent.

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% with a single well-documented 'token' parameter, so the schema carries the load. The description adds no format or validation detail beyond the schema's '0x ERC-20 token contract address'.

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 (reads live) and resource (name, symbol, decimals, total supply of an ERC-20 token on Base), enumerating the exact returned fields. This cleanly separates it from the sibling base_token_balance, which returns amounts rather than metadata.

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 two clear use cases: identifying an unknown token address and formatting raw token amounts. It does not name an alternative or state when not to use it, so it falls short of the explicit routing seen in top-tier definitions.

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