Altcoin Season Index (live + recorded history)

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

The annotations already indicate readOnlyHint=true and openWorldHint=true. The description adds substantial behavior beyond that: the exact index formula (share of top 50 Binance perpetual altcoins beating BTC over trailing 90 days), the altseason/bitcoin-season thresholds (>=75 / <=25), the inclusion of strongest/weakest alts, and the caveat that daily history is 'never reconstructed.' This is rich, honest behavioral disclosure.

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?

The description is a single well-structured sentence that front-loads the user-intent triggers before the return details. Every clause carries useful information: formula, thresholds, return contents, and the reconstruction caveat. No filler 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?

With no parameters and no output schema, the description carries the full burden and fulfills it: it covers when to call, what the indicator measures, how the index is classified, what outputs to expect, and a data-quality warning. Nothing essential is missing for an agent to decide whether and how to invoke this 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 has zero parameters and the schema is 100% covered with an empty properties object. There are no parameter semantics for the description to clarify, so the baseline of 4 applies; the description already explains what data will be returned.

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 opens with explicit call conditions ('Call this when the user asks whether it is altseason, how altcoins are doing against Bitcoin, or about market rotation') and precisely names the resource: the live Altcoin Season Index plus recorded history. It also defines the index calculation and thresholds, making the tool's purpose unmistakable and clearly distinct from generic market index tools.

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?

The description gives strong, explicit when-to-use guidance: altseason questions, altcoin-vs-Bitcoin performance, and market rotation. It does not name alternative sibling tools or state when not to use it, so it stops short of full exclusionary guidance, but the provided context is sufficient for correct routing in most cases.

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