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

The annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior, so the safety profile is covered. The description adds genuinely useful context beyond that: no wallet, no payment, no arguments required, which tells the agent this call is cost-free and credentialless — a real behavioral trait not encoded in the annotations.

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 sentence, front-loaded with the '[FREE]' tag, that states the artifact, its purpose, and the cost/credential profile with no filler. Every clause earns its place.

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 no-argument, read-only preview with no output schema, the definition covers cost, credentials, and intent adequately. The one gap is that it never hints at what the previewed payload contains, which is nominally the tool's whole point, though the title largely compensates.

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 and schema coverage is 100%, so the baseline is 4. The description confirms 'no arguments needed,' aligning with the empty schema rather than contradicting it, and adds nothing misleading.

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 a specific artifact — a free sample response for the signal_delta tool — and distinguishes it from its paid sibling by price and by the absence of a wallet requirement. It stops short of explaining what the underlying signal content actually is (the title's 'what changed since your last pull' carries that weight), so it is clear but not fully self-contained.

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 gives an explicit condition for use — 'before paying 0.05 USDC' — which routes the agent to this preview over the paid signal_delta when it only wants to inspect the response shape. It does not state when the paid tool is the better choice, but the free-vs-paid split makes the alternative obvious.

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