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

Annotations already declare readOnlyHint and idempotentHint, so the safety profile is covered. The description adds genuinely new behavioral facts beyond that: the call is free, no payment transaction occurs here, and the response carries the header names an agent needs to construct the out-of-band HTTP payment.

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, no filler, and the most important constraint — that it is free and that payment happens elsewhere — is front-loaded. Every clause adds information the agent needs.

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?

There is no output schema, so the description carries the burden of describing the return payload, and it does so by listing the exact fields returned. Combined with the free/no-payment caveat, an agent has everything needed to call it and act on the result.

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 per the baseline this sits at 4. The description does add one useful clarification the empty schema cannot convey: the terms pertain to an endpoint whose path includes a {symbol}, which tells the agent the returned terms are symbol-scoped.

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 names the exact resource (x402 v2 payment terms for GET /v1/roadmap/{symbol}) and enumerates the fields returned (price, network, asset, payTo, header names). It does not explicitly contrast itself with perpetual_preview or perpetual_status, but 'Payment is made over HTTP, not through this tool' separates it from any sibling that would perform the actual call.

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?

It clearly establishes the context of use (fetch terms before paying for the protected endpoint) and gives an explicit exclusion: payment is not performed through this tool. It does not spell out a 'call this first, then pay over HTTP' sequence or name the sibling tools, so it stops short of full when/when-not guidance.

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