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

Annotations already declare readOnly, idempotent, non-destructive and open-world behavior, so the description only needed to add value — and it does: it discloses that the supply is formatted using the token's decimals, that bytes32 name responses are handled, and that each call costs $0.005 USDC via x402 on eip155:8453. It stops short of describing failure modes (non-ERC20 or non-verifying contracts) or return shape.

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 tight sentences, front-loaded with the resource and followed by implementation and cost details. Minor redundancy: the opening sentence duplicates the tool title verbatim, which costs a little space without adding 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?

For a two-parameter read-only lookup with no output schema, the description covers what is returned (name, symbol, decimals, formatted total supply), how it is obtained (direct contract reads, bytes32 handling), and the cost model, which is enough for an agent to call it confidently.

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 50%: `chain` is documented with its allowed values and `address` is constrained by a regex pattern, but the address parameter has no prose explanation. The description only implicitly reinforces 'the chosen chain' and the token-contract nature of the address; with coverage at 50% it does not fully compensate.

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?

Names a specific resource (ERC-20 token metadata) and the exact on-chain functions read (name, symbol, decimals, totalSupply), plus the chain scoping. Distinguishable from siblings like evm_balance (native balance), evm_contract (arbitrary calls) and evm_units (unit conversion).

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?

Usage is implied by the resource (fetch token metadata from a contract address), but there are no explicit when-to-use/when-not rules or pointers to alternatives such as evm_contract for non-standard tokens. The x402 pricing note is the only operational guidance added.

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