x402_fetch

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

With no annotations, the description carries the full behavioral burden. It discloses significant non-obvious behavior: automatic 402 payment handling, support for Base/Solana/Casper, and that wallets/payment details are hidden from the agent. It does not mention payment costs, failure behavior, or response format, but it covers the most important hidden traits.

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?

Three short sentences with no fluff. The core action, automatic payment behavior, supported chains, and privacy property are front-loaded. Every sentence conveys useful operational information.

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 payment-related complexity and lack of annotations/output schema, the description conveys the core behavior well. The main gap is that it does not describe what is returned (raw response, status, parsed body) nor explicitly caution that invoking it may incur payment, so an agent has to infer some operational expectations.

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 is 3. The description adds only 'optional body' as extra context, which lightly reinforces the schema but does not deepen understanding of method/chain/body semantics beyond what the parameter descriptions already provide.

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 states a specific verb ('Fetch') and a specific resource ('any x402-paid endpoint'), and clarifies that payment challenge handling is automatic. This clearly differentiates it from sibling discovery/health/description tools like x402_search and x402_describe, which do not actually fetch paid endpoints.

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 phrase 'Fetch any x402-paid endpoint' and 'Just provide a URL and optional body' establishes the core use case: call this tool when you have a concrete x402 URL to invoke. It does not explicitly name sibling alternatives or state when not to use it, but the context makes the primary usage clear.

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