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

The description discloses the index formula, data sources (Alternative.me, CoinGecko, Coinbase, OKX), update frequency (hourly), historical depth (to 2018), and the Gold tier requirement for history, which goes well beyond the readOnlyHint annotation. No contradiction with annotations.

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 dense sentence packed with valuable info, followed by usage guidance and an update note. It is efficient and front-loaded, though slightly long. No wasted words.

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?

With no output schema, the description names the key return fields (composite_score, sentiment_component, volatility_component, liquidity_depth), explains the index construction, and covers the optional parameter behavior and access tier. This is comprehensive for the tool's complexity.

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 only parameter 'days' is fully described in the schema (100% coverage), so the description need not add much. It does reinforce the hourly/history context but does not add significant new meaning beyond the schema.

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 returns a 0-100 crypto sentiment and volatility regime index, with a specific formula, data sources, and output components. The verb 'Returns' and the resource are explicit, and the description distinguishes it as a sentiment/volatility index tool among many siblings.

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?

'Call when the user asks about crypto market sentiment, fear and greed, Bitcoin volatility, risk regimes, or market mood, or when timing portfolio rebalancing, defensive hedging, or crypto entry/exit decisions' provides clear context for when to use. It lacks explicit exclusions or named alternative tools, but the guidance is specific and actionable.

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