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

Annotations only declare readOnlyHint and openWorldHint, so the description's disclosure that the tool is deterministic with no LLM, plus the required $0.004 USDC x402 payment passed in _meta['x402/payment'], adds genuinely useful behavioral context an agent cannot get from annotations. It stops short of describing failure behavior, e.g. what happens for an EOA address where isContract would be false.

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?

Purpose is front-loaded, followed by scope, behavioral notes, a concrete example and pricing — all sentences carry information. The inline example output is bulky but justified because no output schema exists.

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 no output schema, the description compensates by enumerating returned fields and giving a full example response, and it discloses the payment requirement and supported chains. Only edge-case behavior (non-contract addresses, missing metadata) is left unaddressed.

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 the baseline is 3, but the worked example supplies a canonical checksummed address and shows chain="base" in use, clarifying expected formats and the default. Chain values are already listed in the schema, so the added meaning is modest.

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?

The description names a precise resource and enumerates exactly what is returned (name, symbol, decimals, total supply, bytecode presence), which sharply bounds the tool's scope and implicitly separates it from token_price or token_safety. It never explicitly names a sibling, so it falls short of a 5.

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 only implied: it says the tool works for a token contract on Base, Ethereum, Arbitrum or Optimism, from which an agent can infer when it applies. There is no explicit 'use this instead of token_price/token_safety/contract_abi' routing guidance, which would be valuable given several overlapping siblings.

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