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

Annotations already declare readOnly/idempotent/non-destructive, but the description adds real behavioral context beyond them: what it screens (OFAC sanctions, owner powers, unlimited approvals), the exact output form (verdict + receipt), and crucially the pricing model ($0.06/call over x402, prepaid header for unlimited, no free tier, no API key). That pricing/auth detail is valuable and not in annotations. Doesn't contradict readOnlyHint — decode + onchain screen is a read.

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 key verdict concept, but it is dense and repetitive — the unlimited-approval drain vector is mentioned multiple times, and pricing/header detail sprawls across several clauses. Every sentence mostly earns its place, but tighter structuring would help.

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?

Covers what the tool decodes, the verdict output (also backed by an output schema), the screening scope, and the pricing/auth requirement. Given an output schema exists, return values needn't be spelled out. Minor gap: doesn't explain what HOLD triggers versus STOP, which an agent selecting the tool would want.

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% and both params are described there, so the schema does the heavy lifting. The description reinforces 'Required input: data' which aligns with the schema's required field but adds no format/semantic detail beyond it.

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+resource: decodes raw unsigned calldata (approve/permit/transfer/setApprovalForAll) and returns a GO/HOLD/STOP verdict with sanctions screening. This is clearly distinguishable from siblings like tx_decode, decode_selector, and safe_approve by its pre-signing risk-verdict framing and named calldata types.

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?

Positions the tool at the riskiest moment (before signing) and notes 'No simulation needed' which implicitly contrasts with simulate_tx, but does not explicitly name sibling alternatives or state when NOT to use it. Clear context, no explicit exclusions.

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