Quote x402 Resource

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

With no annotations, the description carries the burden and does disclose the critical trait: no signing and no payment submission, i.e. a safe read-only probe. It does not describe error behavior, network cost, or that wallet/profile resolution is required for the delegation answer, leaving some behavioral gaps for a 10-parameter tool.

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 tight sentences with no filler; the core action is front-loaded and the outcome it reports follows immediately. 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?

For a 10-parameter tool with no output schema, the description states the purpose, the safety behavior, and broadly what is returned. It stops short of describing the response shape or the meaning of the ERC-7710 delegation/fee result, but the fully documented schema covers the invocation side.

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 every parameter (url, body, chain, method, headers, walletId, profileId, timeoutMs, tokenDecimals, maxResponseBytes) is already documented with defaults and constraints. The description adds no additional syntax, format, or inter-parameter semantics beyond what the schema provides, 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 ('Probe') applied to a specific resource ('x402-protected HTTPS resource') and specifies what is reported. The phrase 'without signing or submitting payment' cleanly separates it from the paying siblings (agent_x402_pay, veil_pay_x402) without needing to name them.

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 implies the usage context (probe before committing to payment) but never states it explicitly or names alternatives such as agent_x402_pay. An agent can infer when to use it, but there is no explicit when/when-not guidance or sibling routing.

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