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

Annotations already declare readOnly, openWorld and idempotent, so the safety profile is covered. The description adds genuinely non-obvious context: both series are free, each carries its own timestamp and source (signalling possible staleness/skew between the two), and citation/attribution is legally required.

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 usage cue is front-loaded and the data sources follow immediately. The trailing licensing/attribution text is verbose but is compliance boilerplate an agent may need verbatim, so it earns most of its space.

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 input params and no output schema, the description does the work of explaining what comes back: two series, each with timestamp and source. It omits scale/units (e.g., the 0-100 Fear & Greed range) and whether a history window is returned, which are minor remaining gaps.

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 takes zero parameters, so there is nothing to disambiguate and the schema is empty by design; baseline 4 applies. The description implies the returned data is fully self-contained with per-source timestamps.

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 concrete resources precisely: Crypto Fear & Greed from alternative.me and the VIX daily close from FRED. The framing as a 'quick risk-sentiment read' implicitly separates it from the macro-regime and macro-calendar siblings, though it never names an alternative explicitly.

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?

'Use this when you need a quick risk-sentiment read before acting' gives a clear triggering context tied to a decision point. It stops short of stating exclusions or pointing to get_macro_regime/get_macro_calendar as the alternative for deeper macro context.

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