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

With no annotations supplied, the description carries the full behavioral burden, and it does disclose the data source, the value's scale, and that access is free with no payment. It omits update cadence/caching, whether the value is a snapshot or live, and any rate-limit behavior, leaving real gaps for a no-annotation tool.

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 short sentences with zero filler: identity and scale first, then source and cost. Every clause carries information an agent can act on.

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 zero-parameter read tool, the description covers what the metric is, its range, its source, and the absence of payment friction. The remaining gaps are freshness/cadence details, which are minor for a single-value lookup.

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 the baseline is 4 and nothing in the description needs to explain inputs. The stated 0-100 range usefully characterizes the single returned value even though no output schema exists.

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 names a specific metric (Crypto Fear & Greed Index), its scale (0-100), and its upstream source (alternative.me), which is enough for an agent to recognize it as the sentiment-reading tool rather than a price, funding-rate, or risk tool. It stops short of explicitly contrasting itself with any sibling, so 4 rather than 5.

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?

There is no when-to-use or when-not-to-use guidance and no named alternative. The only implicit routing hint is 'Free, no payment,' which signals there is no key or billing step, but it never says which situations call for the sentiment index versus get_price or market_brief.

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