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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=true, and idempotentHint=false; the description is consistent ('reads or computes only and changes nothing') and adds genuinely non-obvious detail: pricing ($0.01/call, first 25 free), malformed address returning 400 uncharged, and that repeats are charged. However, it doesn't mention latency, caching, or output format beyond field names. With annotations covering the safety profile, this is solid but not maximal.

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-loaded with the core action, then usage, then pricing and error behavior. Dense but every sentence carries relevant information; the pricing/examples block is slightly crammed alongside the capability statement, keeping it short of a 5.

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?

No output schema exists, and the description explains what is returned (bytecode size, proxy status, implementation address), plus the failure mode (400, uncharged) and cost model. An agent has everything needed to call it and interpret the result.

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% for the single 'address' parameter, so the schema already carries the semantics. The description adds only a concrete example address and the 400 behavior for malformed input, which is useful but marginal beyond baseline.

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 ('Check whether a 0x address on Ethereum is a smart contract or a plain wallet') and enumerates the outputs: bytecode size, EIP-1167 minimal proxy detection, and implementation address. It also distinguishes itself from eth_proxy and check_counterparty, so an agent can route correctly without opening schemas.

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?

Explicit when-to-use ('before sending funds or approving a spender') and names the alternative for a different need ('for a fuller risk verdict use check_counterparty'). The condition selecting the sibling is stated, not implied.

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