Explain an EIP-712 signature request

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

Annotations already declare readOnly, idempotent, non-destructive, open-world, so the safety profile is covered. The description adds genuinely new behavior: uncovered messages are marked NOT CLEAR-SIGNED and returned as sent, and the domain must carry chainId and verifyingContract. It does not describe the shape of the explanation output, but that is a minor gap.

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?

Four short sentences, front-loaded with the core purpose and ending with the read-only note. Dense but every sentence carries information; the ERC-7730 analogy is slightly decorative but aids interpretation.

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?

For a nested-object tool with no output schema, the description covers purpose, the uncovered-message return behavior, and a key domain requirement. What an agent still lacks is any sense of the explanation's output structure, but the essentials for correct invocation are present.

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 baseline is 3. The description does add one useful constraint beyond the schema — that the free-form domain object needs chainId and verifyingContract — but says nothing about the account parameter or the types/primaryType/message structure.

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 ('Explain an EIP-712 signature request (eth_signTypedData_v4)') and grounds it with concrete examples (token permit, order) plus the ERC-7730 wallet framing. This clearly separates it from explain_transaction and simulate_transaction, which operate on different artifacts.

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 makes clear this is for typed-data signature requests rather than transactions, and notes the fallback behavior for messages without a descriptor. It does not explicitly say 'use explain_transaction instead when X', so the routing to siblings is implied by the artifact type rather than stated.

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