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

Annotations already mark it read-only, idempotent, and non-destructive. The description adds per-call cost of $0.001 USDC, the supported chain set, and byte-identical equivalence to a REST GET endpoint with a worked example. It does not describe behavior for non-contract addresses, but the output schema exists and there is no contradiction with the annotations.

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 core value proposition before cost, chains, and REST equivalence. No filler; the endpoint example is compact and informative rather than redundant. Every sentence earns its place.

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?

Between the output schema, the annotations, and the description's cost/chain/endpoint details, nothing needed to call the tool correctly is missing. It would be marginally improved by naming exactly which interface standards are covered, but the phrase 'supported-interface answer' and the output schema cover that territory.

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%: chain already lists all supported keys and address is described as 'contract to fingerprint'. The description's only extra parameter signal is the example URL showing chain=base and a 0x-prefixed address, which does not substantially change how an agent would populate the fields. Baseline of 3 is appropriate when the schema already carries the parameter documentation.

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?

The description names a concrete deliverable — bytecode size plus supported-interface answers — and frames it as a pre-flight check for whether an address is a contract and which standards it claims. This differentiates it from sibling tools like chain_bytecode_fingerprint, chain_bytecode_capabilities, and chain_token_meta by emphasizing a combined one-call fingerprint. The verb 'check' is generic, but the resource and outcome are specific.

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?

It explicitly states when to reach for it: before interacting with a token address, as a pre-flight. The 'one call' framing and the cost/chain details give clear context for use. It does not name alternatives or exclusion criteria, leaving the agent to infer the boundary against chain_bytecode_fingerprint and chain_bytecode_capabilities, but the guidance is still strong.

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