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

With no annotations provided, the description carries the full behavioral burden. It discloses meaningful traits beyond the schema: the call costs $0.01 via x402, data is live from Blockscout, and it is a one-call replacement for running an RPC. It does not cover rate limits, failure behavior, or auth prerequisites, so it is strong but not exhaustive.

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 payload and scope, the use case, and the data-source/value proposition. The concrete output fields are front-loaded, and there is zero filler or repetition of the tool name.

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 and no annotations, the description covers the returned fields, supported chains, cost, and data freshness, which is enough for an agent to call the single required parameter correctly. The gaps are the undocumented x_payment parameter and unspecified error behavior for unsupported inputs, which keep it from 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 67%, with address and chain already described. The description adds some value by clarifying that address must be an ERC-20/721 token contract and by listing the supported chains, but it leaves x_payment completely unexplained in both the schema and description, and it adds no format or syntax detail beyond the schema.

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 states a specific verb and resource with precise scope: it returns 'total supply, holder count, decimals, and live USD price / market cap' for 'any ERC-20/721 token contract' across six named chains. The listed fields and the ERC-20/721 target clearly distinguish it from siblings like chain_token_identity and chain_native_balance without needing to open the schema.

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 second sentence gives explicit use-case context: 'the supply read trading, valuation and risk agents make to size circulating supply, dilution and holder distribution before pricing or trading a token.' This tells an agent when to reach for this tool, but it does not name alternatives or state when not to use it, stopping short of a 5.

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