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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds genuine context beyond them: the metric's construction (top 50 coins, 90-day window) and the interpretive thresholds for altcoin vs Bitcoin season, plus the return window of 12 month-end readings. No pagination or freshness caveats, so not a 5.

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 dense sentence, front-loaded with the resource name and metric definition, followed by the returned window. Every clause (scale, sample, lookback, thresholds, history length) carries information an agent needs; nothing is padding.

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 carries the burden of describing return values, and it does: a current 0-100 reading plus 12 month-end readings. Combined with threshold interpretation and full annotation coverage, an agent has everything needed to call and interpret this zero-arg read tool.

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 per the rubric the baseline is 4 and there is nothing for the description to clarify. It correctly does not invent parameter semantics.

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 resource (Altcoin Season Index) and defines it operationally: 0-100 scale, share of the top 50 coins beating Bitcoin over 90 days, with explicit 75+/25- thresholds. That level of precision makes it unmistakable against siblings like get_market_snapshot or get_cycle_indicators, which cover different metrics.

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 implied rather than stated: an agent can infer you call this when you need the altcoin-vs-Bitcoin rotation reading, but there is no explicit when-to-use, when-not-to-use, or named alternative (e.g., get_market_snapshot for broad market context). Adequate but leaves routing to inference.

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