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

With no annotations, the description carries the full behavioral burden. It does disclose the returned content (sample count, first and latest timestamps, stale flag) and that it is free versus premium, but says nothing about permissions, rate limits, or whether the result is cached.

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 tight sentences with no waste. The purpose is front-loaded and the pre-purchase check is stated second, which matches the natural reading order.

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?

There is no output schema, so the description usefully enumerates the fields returned (sample count, timestamps, stale flag). For a zero-parameter read tool this is close to complete, missing only edge-case behavior such as what a coin with no archive data looks like.

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 no parameter semantics to convey; the baseline for a parameterless tool is 4. The description appropriately does not invent inputs.

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 states a specific resource and scope: free archive coverage and freshness for each recorded coin, and frames it as a preview step before premium data. It is clearly distinguishable from premium siblings like kimchi_premium_stats, though it does not explicitly differentiate itself from the near-identical preview_research_coverage.

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?

It gives clear usage context: check coverage before buying premium statistics or history. This tells the agent the situation that selects this tool, but it names no alternative tool and states no exclusions, so it stops short of full when/when-not guidance.

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