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

Annotations already establish readOnly, idempotent, non-destructive, open-world behavior, so the bar is lower; the description adds real value by enumerating return contents and explicitly flagging that unknown identity or missing source data comes back unavailable rather than fabricated. It does not discuss the paid x402 call flow or the cost in the body (only the title hints at $0.003), leaving payment behavior to the schema.

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?

A single front-loaded sentence that leads with the trigger and packs the return inventory into a compact list. It is dense but not padded; the only minor cost is a long run-on clause enumerating fields.

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 carries the burden of describing return shape, which it does well by listing the fields inspected. Annotations cover the safety profile and the schema covers the payment/holder mechanics, so what remains missing is only alternative-tool routing and rate-limit behavior.

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, address, payment, and holderWallet are already documented with examples and the holder pricing rules. The description adds nothing to parameter meaning beyond restating that Ethereum/Base are the chains; 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?

States a specific verb ('inspect') and resource (Ethereum/Base address) and enumerates exactly what is returned: EOA vs contract vs EIP-7702 delegation, verified source name, proxy evidence, ETH/USDC balances, nonce, first-seen evidence, labels. It does not differentiate itself from overlapping siblings like name_resolve, x402_seller_check, or watchtower_check, so it stops 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?

'Use when an agent needs to inspect an Ethereum or Base address' gives a clear triggering condition plus an explicit limitation ('Unknown identity or missing source data is explicitly unavailable'), which tells the agent not to rely on it for unknown addresses. It offers no when-not guidance or routing to alternative sibling tools for overlapping lookups.

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