Retrieve the current Crypto Fear & Greed index to assess crypto market sentiment. This pay-per-call tool returns the index value for AI agents, enabling data-driven decisions.
Crypto Fear & Greed index ($0.01 USDC/call).
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description must carry the full behavioral burden. It does disclose one meaningful trait (the $0.01 USDC/call fee), which is useful for an agent deciding whether to invoke it. However, it does not state read-only behavior, what the call returns, or failure/error characteristics, leaving significant gaps.
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 a single compact phrase with no wasted words. The price disclosure earns its place by adding operational information an agent needs before invoking a paid tool.
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 is adequate but thin. It identifies the resource and cost, yet does not explain what the tool returns (e.g., current index value, scale, interpretation) or how to use the result.
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 has zero parameters, and the schema covers 100% of them, so the description is not required to add parameter meaning. The baseline of 4 applies; the description neither needs nor adds param details.
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, recognizable resource ('Crypto Fear & Greed index') which clearly identifies what the tool provides. It lacks an explicit verb like 'get' or 'returns', but the noun phrase makes the purpose inferable and distinguishes it from siblings like x402_crypto or x402_sentiment.
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 guidance is given on when to use this tool versus alternatives. The description only states the resource and cost, with no context about use cases, exclusions, or comparisons to sibling tools like x402_crypto.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.