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

Annotations only say read-only and open-world; the description adds material behavior the agent cannot infer: the $0.005 USDC Base charge, that unpaid calls return a PaymentRequired, and that x402 clients settle automatically. That pricing/auth disclosure is exactly the kind of context beyond structured fields that matters for invocation.

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?

Two sentences, zero waste: the front-loaded capability list is followed by the operational cost note. The dense enumeration is functional here because each item is a distinct returned field.

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 must enumerate return content — and it does, item by item. Combined with the payment behavior and the chain option, an agent has everything needed to decide and invoke correctly.

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 0%, so the description carries the burden. It explains that the tool operates "on Base or Arc," mapping the chain enum to concrete meaning, and address is self-evident from the pattern. It doesn't discuss defaults or format beyond that, keeping it at 4 rather than 5.

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 ("Preflight") plus resource ("any address") and enumerates exactly what is reported: EOA vs contract vs 7702 delegation, proxy implementation/admin, owners, Safe threshold, ERC-20 metadata, balances, verification, risk flags. This is clearly distinct from siblings like usdc_balances or verify_usdc_payment, which cover narrower slices.

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?

"Before paying or approving it" gives a clear triggering condition and the payment mechanics (x402 auto-pay for MCP clients) tell the agent what to expect operationally. It stops short of naming alternatives or exclusions, so it lands just under an explicit when/when-not statement.

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