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

Adds material context beyond the annotations: the $0.001 USDC-on-Base cost, the x402 payment mechanism, and the 'per successful call' billing condition. This explains the readOnlyHint=false/openWorldHint=true combination that would otherwise look odd for a query. It stops short of stating what happens on a failed or contested lookup or any rate limits.

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 filler. The capability is front-loaded and the operational caveat (action trigger, price, payment rail) is packed tightly into the second sentence.

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 fully compensates by naming every returned field (contract vs wallet, bytecode size, proxy status, implementation address) and disclosing the paid-call model. Nothing needed to invoke it correctly is missing.

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?

Only one parameter with 100% schema description coverage, so the schema already carries the load; baseline is 3. The description adds that the address is expected to live on Arbitrum One, which is marginal but real added meaning over the schema's bare '0x address'.

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?

Names a specific verb and resource and enumerates the exact payload: contract-vs-wallet determination, bytecode size, EIP-1167 minimal-proxy flag, and implementation pointer. The chain scoping ('on Arbitrum One') distinguishes it from the many sibling is_contract tools (base_, eth_, op_, polygon_).

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?

Explicitly states the use case: 'Use before sending funds or approving a spender.' That is a clear when-to-use, but it never names an alternative or exclusion, nor does it say why one would pick this over eth_is_contract/base_is_contract beyond the implicit chain difference.

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