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

With no annotations, the description carries the full burden and does disclose real behavior: a per-call price of $0.003 USDC on Base and a settlement rule that invalid input, not-found and upstream errors are not charged. It omits rate limits, latency, and what a 'not-found' response looks like, but the payment/auth behavior is unusually well covered.

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, front-loaded with the verb and scope, with no filler. The parenthetical proxy-standard catalogue is dense but each entry (EIP-1967, ZeppelinOS/USDC, EIP-1167) is materially useful to an agent deciding whether this tool detects a given proxy pattern.

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?

There is no output schema, so the description must describe return values, and it does by listing the classification fields it produces. Combined with the chain coverage and payment terms, an agent has enough to decide and call correctly; only the shape/format of the actual response is left implicit.

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%, so chain, address, and paymentSignature are already fully documented, including the chain list and defaults. The description adds only the count of supported chains and the payment context, not new per-parameter semantics, so the 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 ('Classify') and resource ('any address on 7 EVM chains') and enumerates exactly what is returned: EOA vs EIP-7702-delegated vs contract, code size, nonce, native balance, and named proxy standards. This cleanly separates it from siblings like chain_native_balance or chain_token_info, which return a single facet rather than a full address classification.

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?

'before interacting with it' gives a concrete decision context for when to reach for this tool, and the pricing/settlement sentence tells the agent the cost of a failed call. However, it never names an alternative (e.g., use chain_native_balance for balance-only reads) nor states when not to use it, so routing is implied rather than explicit.

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