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

Annotations already disclose the safety profile (readOnly, non-destructive, openWorld), so the bar is lower. The description adds material context the annotations don't: the $0.002 USDC cost and the x402/Base payment mechanism, which matters operationally before invoking. It stops short of describing freshness/latency of the index.

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 resource and value semantics front-loaded. Minor redundancy in restating 'Crypto Fear & Greed Index' twice, but overall tight and waste-free.

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 simple read-only snapshot with annotations covering safety and no output schema needed, the description supplies the key call-context: value range, interpretation, and price. Only missing sweating detail is data freshness, which is minor.

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 single schema property 'note' has 100% description coverage and is explicitly a no-op ('no parameters required'), so the schema already resolves any ambiguity. The description adds nothing about this field and needs nothing, making baseline 3 appropriate.

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?

Names the specific resource (Crypto Fear & Greed Index) and defines its scale and output shape (0=extreme fear, 100=extreme greed, with classification). No explicit verb and no direct sibling contrast, but the resource is unique enough among the crypto_* tools to be unambiguous.

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?

The phrase 'widely-used market-sentiment signal' hints at why it matters, but there is no when-to-use guidance, no exclusions, and no reference to alternatives. An agent gets no routing help versus the other market/crypto tools.

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