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

With no annotations, the description carries the burden of explaining behavior, and it does disclose computation details and a cost ('Price 0.01 via x402 (USDC on Base)'). However, that cost sentence is truncated/garbled, and the description does not clarify whether the operation mutates anything, exactly what happens to the raw input, or how the price is applied.

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?

The first clause front-loads the purpose, but the second 'sentence' is incomplete and confusing ('Turns raw s Price 0.01 via x402'), which makes the definition feel truncated rather than deliberately concise. A short description should still be grammatically coherent.

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 tool with no output schema and no annotations, the return intent is only partially specified; an agent does not know the underlying data source ('fear and greed' is only implied by the name), the exact response shape, or the cost/payment flow. The garbled pricing sentence adds ambiguity instead of completing the picture.

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% for the single optional wallet parameter, including free-tier credit distinctions, so the description does not need to compensate. It adds no parameter-specific detail beyond what the schema already provides, which matches the baseline.

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 states a clear operation: it returns a 'live computed signal' built as a 'processed analytics layer over market signals,' with three specific outputs: 30-period percentile rank, 4-period momentum, and a plain-language trend verdict. This goes beyond the generic name and makes the resource identifiable, though it does not explicitly name the Fear & Greed index or distinguish it from siblings like processed_fear.

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?

There is no guidance on when to choose this tool over alternatives; sibling candidates such as processed_fear, processed_crypto_prices, or signal_market_stress are never mentioned or contrasted. The only context, 'free credits every month,' comes from the schema rather than the description.

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