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 discloses the price ($0.004 per call), the accepted payment assets (USDC on Arc/Base/Solana, XNT on X1), and the fact that settlement happens inside the second call. The line 'Identity is the contract, never the symbol' is genuinely valuable framing that shapes how results should be read. It omits edge behavior such as whether payment is consumed on a failed or empty result.

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 data description is front-loaded in the first sentence, followed by the interpretive rule and then the payment mechanics. Every sentence carries information, though the payment sentence packs price, three chains and the flow into one long clause that could be split for readability.

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?

For a single-optional-parameter tool with no annotations and no output schema, the description covers cost, payment flow, and the shape of the returned fields (symbol, sharing contract count, verified canonical address). It leaves open whether results are paginated or how 'verified' canonical status is determined, but nothing essential to calling it 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 coverage is 100%, so the baseline is 3, but the description adds meaning the schema does not: the omitted-parameter case (terms returned) and the two-step sign-then-submit lifecycle of `payment`. That is real semantic value beyond 'a signed x402 payment'.

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 states a concrete resource and scope: token symbols on Arc used by more than one contract, plus the number of contracts sharing each symbol and the verified canonical address. That is much more than a restatement of the name 'arc_impostors'. It does not explicitly name a sibling (e.g. arc_token_info or arc_contract_check) to contrast against, so it stops short of a 5.

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 gives an explicit operational procedure: call once without `payment` to receive terms, sign them with your own wallet, then call again with `payment`. This removes ambiguity about how a paid tool is invoked. It does not say when this data is preferable to alternatives like arc_token_info or arc_contract_check, and gives no exclusions.

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