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

Goes well beyond the readOnly/idempotent annotations: discloses provider routing per chain (Blockscout preferred, Ethplorer fallback, Base uses Blockscout), the exact failure mode (503 if the explorer blocks, and not charged), the paid access model (x402 USDC on Base, $0.002 per successful call, PaymentRequired object on unpaid calls), and privacy handling (public tags/ENS only, emails stripped). This is unusually rich operational context.

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?

Front-loads the use case and return shape, then layers routing, privacy, and pricing. Every sentence carries information, though the payment and provider-routing clauses make it longer than typical; it stays readable and non-redundant.

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?

There is no output schema, yet the description enumerates the returned fields and notes the caveat that supply share appears only 'when the explorer provides it.' Combined with the routing, failure, and pricing details, an agent has everything needed to call it correctly and interpret the response.

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 chain, limit, and address are already documented in the schema. The description reinforces semantics ('top N', 'on Base or Ethereum') but adds no format or edge-case detail beyond what the schema provides, so baseline 3 applies.

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 a specific verb and resource: returns the top N holders of an ERC-20 contract on Base or Ethereum, and enumerates the returned fields (rank, address, raw/formatted balance, supply share). The opening clause distinguishes it from address-centric siblings like balances by framing it as token-holder concentration analysis.

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?

Gives explicit triggering context: 'Use when you need who holds a token (concentration, whales, treasury).' That is clear positive guidance, but it never names a sibling alternative (e.g., balances for a single address's holdings) or states when not to use it.

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