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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint, so the safety profile is covered. The description adds real value with the 0/100 scale interpretation and the daily-granularity of the series, but says nothing about the default range, the 30-day cap, or the data source/refresh cadence.

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?

A single tight sentence with the identifying noun and the scale semantics front-loaded. Zero padding or 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 simple one-parameter read tool with annotations covering safety, the description is adequate but leaves gaps: the days window (default and 30-day maximum) and the shape of the returned history are undocumented, and there is no output schema to fall back on.

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?

There is one parameter (days, default 7, max 30) with 0% schema description coverage, so the description is the only place semantics could be supplied — yet it never mentions the parameter at all. 'Daily history' faintly implies a day-count window but gives no default, bounds, or units.

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 specific resource (Crypto Fear & Greed Index) and states what it returns: the 0-100 value with daily history. It is distinguishable from siblings like get_price or global_stats, though it never uses an explicit retrieval verb.

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?

No guidance on when to use this versus alternatives such as global_stats or market_overview, and no stated preconditions. The only implied usage cue is the mention of 'daily history', which hints at multi-day trend analysis but is never articulated.

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