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

The annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the description's behavioral disclosure aligns with those. It adds useful operational context beyond the annotations: it decodes specific function selectors, screens for OFAC sanctions and dangerous owner powers, returns a verdict + receipt, requires no simulation, and discloses pricing/header requirements (x402, $0.06, prepaid credit token, 1 free call/day). This goes beyond a bare read-only marker by explaining what the tool does onchain and what inputs are needed.

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 description is densely packed but well front-loaded: the core question, verdict, and decoding scope appear in the first sentences, followed by risk screening, pricing, and free-tier details. It is long, but every sentence contributes meaningful operational or risk context. The only minor deduction is that pricing and header details could arguably live in a separate billing field, yet they are relevant for an agent deciding whether to call the tool.

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?

Given there is an output schema (the verdict + receipt is described but structured output is presumably in the schema), the description covers the key operational context: required input, what is decoded, what risk checks are performed, pricing, and no-wallet requirement. It doesn't specify whether 'to' is optional in behavior or how sanctions screening handles the destination vs spender, but the tool is simple enough (2 params, no nested objects) that this is not a critical gap. The description is complete for selecting and invoking the tool correctly.

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 schema already documents both parameters. The description reinforces that 'data' is required and adds minimal semantics by saying it is 'raw unsigned calldata (0x…)' — matching the schema. It doesn't add meaning beyond the schema for 'to', but because coverage is complete and the description repeats the required input, a baseline 3 is appropriate.

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 sharp, specific purpose: 'Should the agent sign THIS calldata? GO/HOLD/STOP — The check before the riskiest moment — signing.' It clearly identifies the resource (raw unsigned calldata), the exact actions decoded (approve/permit/transfer/setApprovalForAll), and the output (a GO/HOLD/STOP verdict + receipt). It also differentiates from siblings like tx_decode by emphasizing it is a pre-signing risk screen rather than a generic decoder.

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?

The description states when to use it: before signing calldata, particularly to catch unlimited-approval drain vectors, and states what it does not involve ('No simulation needed — pure decode + onchain risk'). It doesn't explicitly name alternative tools to use instead, but the unique pre-signing GO/HOLD/STOP framing and explicit 'no simulation' note make the intended context clear. With a sibling list full of risk and decode tools, an explicit alternative would have been stronger.

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