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

Beyond the read-only/idempotent annotations, the description discloses rich operational context: the ordering rule that interface support is read from the contract's own declaration first and only inferred when absent (with the NFT totalSupply caveat), plus the full payment model — $0.002/call over x402, prepaid x-credit-token header, 1 free call/day, no API key. These are meaningful traits an agent cannot get from the schema.

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?

The core question and its answer lead the text, so it is well front-loaded, and the ordering caveat is a genuinely useful clause. It is dense and the payment/pricing sentence is somewhat tangential to identity detection, keeping it just 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?

With an output schema present, return values need not be explained, and the annotations already cover the read-only, idempotent, open-world profile. The description completes the picture with detection method, inference ordering, payment/auth requirements, and the required input — nothing an agent needs to call 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?

Schema description coverage is 100% for the single 'address' parameter, so the schema already carries the semantics and the description only restates 'Required input: address'. It adds no format, chain, or checksum guidance beyond that, so the baseline 3 for full schema coverage 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?

The description opens with a precise, well-scoped question ('what sits at a Base address: contract or plain wallet') and enumerates exactly what it returns: standard detection (ERC-721/1155 via ERC-165, or ERC-20 shape) plus name, symbol, decimals and code size. This is a specific verb+resource that reads distinctly from siblings like contract_owner or token_info without needing to name them.

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 implied by the clearly stated scope (identifying an address as wallet vs contract and its standard), and 'Required input: address' reinforces the entry condition. However, it names no alternatives or exclusions — nothing tells the agent when to pick this over contract_abi, proxy_check or token_info, so selection guidance 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.