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

Annotations already declare readOnly, idempotent, non-destructive, openWorld. The description usefully adds that no wallet, payment, or arguments are required, which is real auth/cost context beyond the annotations. It does not describe the sample's contents, but the free/no-auth detail is valuable.

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?

A single front-loaded sentence beginning with the [FREE] marker, so the key distinction is immediately visible. Efficient and appropriately sized for a zero-param preview.

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?

For a zero-param preview with no output schema, the description covers what the agent needs: it returns a sample of crypto_news, is free, and needs no auth. Minor gap is not describing the sample's content, but the preview concept is complete.

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?

Zero parameters, so the baseline is 4. The description reinforces this with 'no arguments needed', consistent with the empty schema. Nothing further is required.

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 purpose: it is a free sample response for the crypto_news tool, letting the agent see the response shape. This cleanly distinguishes it from the paid sibling crypto_news without needing to open either schema.

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 communicates when to use it (before paying 0.001 USDC) and names the parent tool it previews, which routes the agent between preview and paid version. It stops short of an explicit 'use crypto_news for real data' statement, so it is clear but not fully spelled out.

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