Crypto market indices (Fear & Greed, BTC dominance, euphoria)

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

Annotations already declare readOnlyHint and openWorldHint. The description adds useful context: the refresh interval (~30 minutes) and the specific components included (today/yesterday's Fear & Greed, Bitcoin dominance, total market cap, Retail Euphoria). This goes beyond the annotations without contradicting them.

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 two sentences, front-loaded with the usage trigger, and packs detailed data points without redundancy. Every sentence earns its place with no fluff.

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?

Given the tool's simplicity (no parameters, no output schema, simple data retrieval), the description is fully complete: it states what to call it for, what data it returns, and the refresh cadence. No critical information is missing.

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, so the schema provides no semantics. The baseline for 0 params is 4. The description compensates by explaining exactly what data will be returned, making the parameterless invocation clear.

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 clearly states the tool's purpose: answering questions about overall crypto market sentiment or macro state. It lists specific data points (Fear & Greed, BTC dominance, total market cap, Retail Euphoria) and distinguishes itself from sibling tools that focus on narrower metrics like funding, liquidations, or options flows.

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 description explicitly tells when to use the tool ('when the user asks about overall crypto market sentiment or macro state'). It does not explicitly mention alternatives or when not to use it, but the sibling list provides context and the instruction is clear enough for an agent to select it appropriately.

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