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

The annotations already declare readOnlyHint, idempotentHint, and openWorldHint=false, so the safety profile is covered. The description adds rich output semantics beyond that: it defines the three decision outcomes (match, mismatch, unknown), explains what mismatch means (different recipient/amount, or an approval instead of a payment), and warns that 'unknown' must not be treated as safe. This is exactly the behavioral context an agent needs before acting on the 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 description is front-loaded with the core warning ('Anti blind-signing') and proceeds directly into what it decodes, how to call it, and how to interpret decisions. Every sentence earns its place: the supported action list, the parameter guidance, and the decision definitions all serve distinct needs. There is no filler or repetition.

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 the tool's complexity (nested intent object, 4 parameters including optional value), the description is nearly complete. It handles the nested intent shape, defines the decision outputs without needing an output schema, and gives the critical safety caveat for 'unknown'. It leaves minor gaps around the optional value parameter and any chain/coverage limitations, which prevents a perfect score.

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 description coverage is 75%, so the schema already documents data, value, intent, and contract at a basic level. The description adds practical usage detail beyond the schema: it shows how to pass intent:{action:'pay', to, amount}, clarifies that contract is the transaction's `to` field, and reiterates that data is hex calldata. It does not mention the optional value parameter, which keeps it from a 5.

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 gives a specific verb and resource: 'Decodes what a transaction's calldata will actually do' and compares it with declared intent. It even enumerates the supported calldata types (ERC-20 transfer/approve/permit, setApprovalForAll, ownership transfer, native transfer). However, it does not explicitly differentiate itself from sibling tools such as payment_decision or verify_payment_requirements, so the sibling-routing clarity is left to inference.

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 context 'Anti blind-signing' implies the tool should be used before signing a transaction, and the mismatch guidance ('do not sign') reinforces that. But the description never states when to choose this over sibling tools like payment_decision or screen_address, nor does it list alternatives or exclusions. Usage is therefore implied rather than explicit.

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