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

Annotations already declare readOnly, idempotent, open-world and non-destructive behavior, so the bar is lower. The description adds genuinely useful context beyond them: it is free, requires no wallet/payment, and takes no arguments.

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 compact sentences with the [FREE] tag and the pay-to-preview rationale front-loaded. Every clause earns its place; nothing is redundant.

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-parameter, read-only, free preview with no output schema, the description covers what an agent needs: what it returns (a sample response), its cost (free), and its purpose (inspect shape before paying). Only the content of the sample itself is unspecified, which is acceptable for a preview.

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?

There are zero parameters, so the baseline is 4. The description reinforces this with 'no arguments needed,' correctly signaling that the call takes none.

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 action (return a sample/free preview response) and explicitly ties it to the sibling signal_topic_trace, so the agent can tell it apart from the paid tool. It does not explain what a 'topic/id trace' actually contains, so the resource is only partially clarified.

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?

Gives a clear use condition: call this to inspect the response shape before paying 0.06 USDC for signal_topic_trace. It does not state exclusions (e.g., that the data is canned/sample rather than live), but the when-to-use is explicit enough.

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