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

With no annotations, the description carries the burden and does add real behavioral context: it discloses the paid x402 flow (0.003 USDC per call on Base), which is a prerequisite an agent must know before invoking. It also signals conditional output ('ABI when available'), implying unverified/EOA addresses return partial results, though it stops short of describing error or rate-limit behavior.

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, both earning their place: the first front-loads what is returned, the second front-loads the pricing constraint. No filler or restatement of the tool name.

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 properly enumerates the return payload (contract flag, bytecode size, Sourcify status, ABI) and notes the ABI is conditional. It is nearly complete for a one-parameter read tool; only the response shape for non-contracts and failure modes are left unstated.

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 coverage is 100% for the single address parameter, so the baseline is 3. The description adds only the chain scoping ('on Base'), which narrows the meaning of the address slightly but adds no format or validation detail beyond the schema's example.

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+resource ('Contract check and ABI for an address on Base') and enumerates exactly what is determined: contract-ness, bytecode size, Sourcify verification, and ABI. This clearly separates it from siblings like evm_balance or evm_token_info, which report holdings rather than code properties.

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?

Usage is only implied: an agent can infer you call this when you need to know whether an address is a contract or need its ABI. There is no explicit when-to-use/when-not, no mention of alternatives (e.g. evm_decode for ABI-driven decoding), and no guidance for EOA inputs.

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