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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful context beyond that: the exact cost ($0.01 USDC), the accepted chains (Base/Polygon), the 24-hour publish duration, and the explicit warning that it does not itself pay. Return format is left to the output schema.

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, front-loaded with the core action and the key constraint ('this tool does not pay') placed last for emphasis. No filler.

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?

Output schema exists, so return-value explanation is unnecessary. The description covers cost, chain, duration, and the non-payment boundary, which is everything an agent needs to invoke it correctly for a two-parameter prepare tool.

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%, with both 'vault' (address pattern) and 'label' (optional title, max 60) fully documented in the schema. The description adds no syntax or format detail beyond what the schema already carries, 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 (returns) and resource (the x402 payment request to publish a portfolio page for a vault), plus duration and price. An agent can immediately tell this apart from sibling prepare tools like stocks_signals_prepare or bridge_prepare_payment by the named target artifact.

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?

Explicitly routes usage: 'Pay it with your own x402 client. This tool does not pay.' That is a clear when-to-use and a when-not-to (this is preparation, not payment). It stops short of naming the sibling that performs payment or the follow-up flow, so it misses the top tier.

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