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

With no annotations, the description carries the full behavioral burden. It does disclose that the value comes from alternative.me and that it is a sentiment index, signaling an external data dependency. However, it does not state whether data is live or cached, how failures behave, or what the response structure looks like.

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 description is compact at one sentence, but it opens with 'Fear Greed:' which duplicates the tool name, and later repeats 'Fear-and-Greed index', creating mild redundancy. The core facts are front-loaded, but the wording could be leaner.

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 tool with no output schema and no annotations, the description supplies the essential facts: what metric, its scale, the classification, and the source. It does not specify the exact response format, but the simple semantic content makes this sufficient for an agent to call the tool correctly.

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 zero parameters and schema description coverage is 100%, so there are no parameter semantics to explain. The description's mention of the 0-100 range and classification is unrelated to inputs but appropriately frames the output for this no-parameter tool.

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 identifies a specific resource – the Fear-and-Greed index – with its numeric range (0-100), the classification, and the external source (alternative.me). This differentiates it from sibling crypto tools like x402-crypto-price and x402-crypto-trending, though no explicit verb such as 'returns' or 'gets' is used.

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?

No explicit when-to-use or when-not-to-use guidance is given, and no alternative tools are named. The 'Crypto market sentiment' framing implies the use case, so an agent must infer when this tool is appropriate rather than being told directly.

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