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

With no annotations provided, the description carries the behavioral disclosure burden. It reveals that the tool does not execute a purchase but returns a permit payload requiring EIP-712 signing, which is critical non-obvious behavior. However, it omits follow-up steps (e.g., whether a later confirmation call is needed) and details about permit expiry or side effects, leaving some ambiguity.

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 three concise sentences, front-loaded with the 'BUY, HUMAN WALLETS ONLY' label followed by clear instructions and audience specification. Every sentence contributes value with no redundancy.

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?

The description is complete enough for its intended human-wallet audience: it states what is returned (EIP-712 permit payload) and who should use it, while actively diverting AI agents to the correct sibling tool. It does not fully describe the end-to-end flow (no mention of confirm_purchase or what happens post-signing), but the absence of an output schema makes the return-value disclosure somewhat basic.

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 100%, so the baseline of 3 applies. The tool description itself adds no parameter-specific meaning, but the schema already documents all parameters thoroughly, including size/color nuances and requirements for specific listing types.

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 clearly states the tool's function: it returns an EIP-712 permit payload to be signed, with a 'BUY' label and explicit human-wallet-only scope. It also distinguishes itself from the sibling initiate_agent_purchase by directly stating which tool AI agents should use instead.

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 provides explicit usage guidance: AI agents must NOT use this tool and should use initiate_agent_purchase instead, while human wallet apps (browser/hardware) should use it. This clearly communicates when to use vs. alternatives.

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