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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so the safety profile is covered. The description adds the detection scope (approvals, permits, drainer selectors) and the $0.002 USDC on Base cost, which is genuinely useful context, but says nothing about latency, rate limits, or failure modes.

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?

Two tightly packed sentences with zero filler; the core capability leads and the pricing detail trails. Every clause earns its place.

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?

With an output schema present, return values need not be described, and the single param is fully documented. Annotations cover the safety profile, so the description only lacks routing guidance against the sibling security tools.

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% for the single calldata parameter, which the schema already documents as hex (0x...). The description adds no format, encoding, or constraint detail beyond that, so the baseline 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 pair (decodes and inspects) and a precise resource (EVM transaction calldata / ABI payloads), plus the threat classes it targets (unauthorized approvals, permit signatures, drainer selectors). It does not distinguish itself from the other security_* siblings (prompt_firewall, url_threat_check, x402_endpoint_verifier), so it falls 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?

Usage is only implied: an agent can infer you run this before signing or executing calldata, but the description never states when to reach for it versus security_x402_endpoint_verifier or pre_trade_agent_gate, nor any prerequisites. No explicit when/when-not guidance.

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