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

Annotations declare readOnlyHint=false and idempotentHint=false, which is somewhat odd for a read operation, but the description clarifies it reads live from the contract and discloses cost ($0.001 USDC on Base via x402) — non-obvious operational context not in annotations. It doesn't contradict annotations and adds payment/auth info.

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, front-loaded with what is returned, then usage and cost. No wasted verbiage.

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?

Given a single-parameter read tool with full schema coverage and no output schema, the description covers purpose, use cases, and payment model. Since there's no output schema, it could explicitly state the return shape (e.g., object with those four fields), hence not a 5.

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% and the single parameter 'token' is fully described as a 0x ERC-20 contract address. The description adds no format details beyond the schema, so baseline 3 is appropriate.

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 precisely what is retrieved (name, symbol, decimals, total supply) for a specific resource (ERC-20 token on Ethereum), read live from contract. This distinguishes it from siblings like eth_token_balance (which returns balance) and arb_token_info/polygon_token_info (different chains).

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?

Explicitly says 'Use to identify an unknown token address or to format raw token amounts correctly', giving clear use cases. It doesn't explicitly exclude alternatives, but the chain-specific naming and siblings' purposes make the boundary clear.

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