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

With no annotations provided, the description carries the full burden of behavioral disclosure. It states that the tool reads on-chain data, reports invalid or non-ERC-20 addresses as such, is NOT charged in those cases, and costs $0.005 USDC via x402 on Base. This is exceptional transparency for a read-only utility.

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 earning its place: the function, the use case with a concrete caution, and the cost/error behavior. The 1,000,000x example is vivid but relevant, not padding. The structure front-loads the core action before extras.

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?

Despite having no output schema, the description names the returned fields (name, symbol, decimals, total supply) and the code-existence confirmation. It also covers edge cases (no code, non-ERC-20), pricing, and payment rail. An agent knows what to expect and how the call behaves under failure.

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 are already well documented: chain lists the supported networks and default, and address specifies the 0x-prefixed format. The description does not add parameter-level detail beyond the schema, though it contextualizes the importance of decimals. 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?

The description opens with a specific verb and resource: 'Read an ERC-20's name, symbol, decimals and total supply straight from the contract.' This makes the tool's function unmistakable. It does not explicitly contrast with sibling tools like address_info, but the focus on token metadata is distinctive enough to avoid serious confusion.

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?

The description gives an explicit, actionable use case: 'Use before quoting an amount or building a transfer' and explains why decimals matter. It does not name alternatives or state when not to use the tool, but the timing guidance is concrete and useful.

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