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

With no annotations, the description carries the full burden and does well: it discloses return fields (isContract and bytecode size), the absence of an API key or account, the exact cost ($0.005), and the payment rail (x402/USDC). It does not state failure behavior for invalid or non-existent addresses, keeping it short of a 5.

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?

Three sentences, front-loaded with the decision scenario, then the return values, then the exclusions, then the cost/auth facts. Every sentence carries information an agent needs and none is 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?

For a two-parameter read tool with no output schema, the description covers purpose, return shape, cost, and routing. The only gap is behavior on invalid or undeployed addresses (does it error or return false), which matters when bytecode size is part of the answer.

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% and both parameters (chain with its allowed values, address) are documented there. The description adds only the framing of 'destination' for the address and no chain-selection guidance, 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 ('decide whether the destination is a plain wallet or a contract') and names exactly what it returns. It is clearly distinguishable from siblings like evm_balance, evm_code-adjacent tools, and evm_token_safety.

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 (about to send funds, before signing) plus explicit when-not to use, naming the two alternative endpoints (/v1/evm/token-safety and /v1/evm/verdict) with the reason each differs. Nothing is left to inference.

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