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 declares determinism, names the underlying sources (Blockscout and the Base RPC), states what is deliberately absent ('No labels, no scoring, no LLM'), notes it is informational only, and discloses cost ($0.05 per call, paid in USDC over x402). It omits failure/error behavior and latency, 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?

Front-loaded with the deliverable, then the exclusion list, then the commercial/payment terms, so an agent gets the essentials in the first clause. The dense em-dash enumeration is information-rich but slightly heavy for a single sentence.

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?

No output schema exists, so the description must characterize the return value—and it does, enumerating every field group and the flag conditions (fresh <7d, dormant >180d, no ETH, single token, contract). Combined with the disclosed sources and pricing, an agent has everything needed to call and interpret it.

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?

Only one parameter, and the schema already documents it at 100% coverage including the 0x pattern. The description's 'any address: EOA or contract' restates what the schema's parameter description already says, adding minimal new meaning, so the high-coverage baseline of 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?

Opens with a concrete verb+resource ('deterministic Base wallet card for any address') and enumerates the exact payload: ETH balance, first/last activity, tx and token-transfer counts, up to 20 ERC-20 holdings, and named rule-based flags. This clearly separates it from siblings like token_check, token_report, or claim_check, which cover different resources.

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 context is implied by 'Facts an agent can act on; informational only,' which signals a read-only, non-advisory lookup against a single address. However, it never names an alternative tool or states when another sibling (e.g. token_report) would be the better pick, and there are no explicit exclusions.

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