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

Annotations already declare readOnlyHint, openWorldHint=false and idempotentHint, so the safety profile is covered and the trailing 'Read-only' is largely redundant. What the description does add is genuinely useful: the upstream source (BitInfoCharts), the fact that figures are cross-checked four ways, and that results carry an as-of date — signaling snapshot data that may lag.

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 compact sentences with the core metric front-loaded, followed by caveats and provenance. The closing 'Read-only' repeats the annotation and is the one sentence that does not earn its place.

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 parameters and no output schema, the description carries most of the burden and mostly delivers: metric definition, threshold buckets, unit of analysis, provenance and freshness caveat. It stops short of describing the shape of the response (e.g., per-class coin totals), which would help an agent plan around it.

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 for the description to disambiguate; baseline is 4. The enumerated thresholds in the prose usefully confirm the fixed buckets the caller will receive.

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 concrete resource and metric: address counts at fixed BTC thresholds (0.1 through 10,000) plus how coins split across holder classes. This is far more specific than the name alone. It does not, however, differentiate itself from the sibling get_holders, which an agent could easily confuse with this tool.

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?

Usage is only implied by the content — an agent can infer it is for supply-distribution questions, but there is no explicit 'use this when' or 'use get_holders instead when' statement. The 'Addresses, not people' line is a scope caveat rather than routing guidance.

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