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, and the description adds useful context: the refresh interval ('about every 30 minutes') and the specific data components returned. It does not contradict annotations and adds value beyond the structured metadata.

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 invocation trigger, and lists all relevant metrics in a compact, readable manner. Every sentence provides essential information without redundancy.

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 parameters and no output schema, the description fully covers when to use it, what data it returns, and the data freshness behavior. It is complete for a zero-parameter data retrieval tool.

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 baseline is 4. The description appropriately explains what data is returned without needing to explain parameter usage, and the schema already confirms no parameters exist.

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 explicitly states the tool returns overall crypto market sentiment and macro state indicators, listing specific metrics (Fear & Greed index, Bitcoin dominance, total market cap, Retail Euphoria composite). This clearly distinguishes it from sibling tools that focus on liquidations, ETF flows, or funding rates.

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 begins with 'Call this when the user asks about overall crypto market sentiment or macro state,' providing explicit guidance on when to invoke the tool. It does not explicitly mention when not to use it or name alternatives, but the contextual scope is clear.

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