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

Goes beyond the readOnlyHint annotation by stating that no funds move until the wallet or user authorizes the x402 request, which reassures the agent this is a non-mutating prep step. It stops short of describing the response shape or what the 'wallet steps' actually look like.

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 sentences, zero filler, with the deliverable (paid URL and wallet steps) front-loaded and the safety caveat second. Nothing could be removed without losing 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?

With zero params and no output schema, the description covers the essentials: what comes back and the fact that funding is deferred. A note on what the caller does with the returned URL (i.e., the follow-up step) would close the remaining gap.

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?

The tool takes no parameters, so there is nothing for the description to disambiguate; the baseline applies. No parameter confusion is possible given the empty, additionalProperties:false schema.

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?

Specific verb (prepare/return) plus the exact artifacts (paid URL and wallet steps) and the resource (the independent ETH 4H setup). The asset-specific naming separates it from prepare_btc_4h_purchase and peers, though it never explains how it differs from the generic prepare_4h_setup_purchase.

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?

No explicit statement of when to call this versus the sibling prepare_* tools or discover_4h_setups; the asset name implies the case but the agent must infer it. The only conditional sentence is about authorization of the x402 request, which is a behavior, not a selection rule.

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