x402_fetch

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

With no annotations provided, the description carries the full burden, and it delivers: it discloses the full network behavior (GET, 402 handling, EIP-3009 signature, X-PAYMENT header), the user approval experience, autopay and password rules, per-payment and daily limits, emergency lock, and the explicit warning not to send a password. This is exceptional transparency for an unannotated 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?

The description is longer than average but every sentence carries useful information: process, security, args, and return values are all clearly separated. It is front-loaded with the core purpose and then expands logically. It could be slightly tighter, but there is no filler or 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?

Despite having no output schema, the description enumerates the return fields ('paid, status, http_status, body, and amount/pay_to/settlement when paid') and covers key context such as the active Base network, USDC, payment limits, and the emergency lock. This is more than enough for an agent to decide whether and how to invoke the tool correctly.

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 adds some value for memo by explaining the user sees it in the approval window, and it warns not to send a password, but it doesn't fundamentally extend the schema semantics for either parameter. It essentially restates and clarifies, which is adequate but not extra-rich.

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 opens with a specific verb and resource: 'Fetches an x402 paid resource (a URL)', and then explains the exact HTTP flow (GET, 402, payment, re-request). It clearly distinguishes itself from siblings by naming 'request_payment' as a separate approval flow and by stating that approval works 'exactly as in request_payment', while the other siblings (balances, history, wallet status) are obviously not about fetching paid resources.

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 strongly implies when to use the tool: whenever a URL may require x402 payment, and explains the conditional path when no payment is required. It references request_payment for the approval behavior, giving cross-tool context, though it does not explicitly list exclusions or say 'use request_payment when you only need to send a payment'. Still, the context is clear and actionable.

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