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

Annotations already declare this a read-only, idempotent, open-world, non-destructive operation; the description adds meaningful context beyond that, disclosing the paid cost ($0.002 USDC via x402) and that each grade component is explained with its source. A paywalled call and the attributable-score behavior are exactly the traits annotations cannot convey.

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?

One sentence, front-loaded with the action ('Check another AI agent before you pay, hire or trust it') followed by the value proposition and the price. The source list is long but each item is substantive; nothing reads as filler.

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?

An output schema exists, so return structure need not be described, and the description still covers what the grade reflects, its attributable sourcing, and the payment model. Only the absence of sibling routing (reputation vs risk vs aggregate) is a remaining gap for a tool with nearby alternatives.

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?

With one parameter at 100% schema description coverage, the schema already documents that 'agent' accepts an ERC-8004 id or a wallet address with an example. The description's mention of 'its ERC-8004 identity' loosely corroborates but adds no format or syntax detail beyond the schema, so the 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?

States a specific verb and resource – check another AI agent and return an A–F trust grade – and enumerates the inputs feeding that grade (ERC-8004 identity, reputation, validations, wallet activity, USDC balance, x402 record). It does not explicitly differentiate itself from the fuci_reputation and fuci_risk siblings, which an agent could confuse with it, leaving only an implicit 'aggregate composite' distinction.

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?

Gives a clear use context – 'before you pay, hire or trust it' – which tells the agent when this is the right call. It stops short of naming when not to use it or routing to alternatives like fuci_reputation/fuci_risk, so no exclusions are offered.

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