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

Annotations only declare readOnlyHint and openWorldHint; the description adds real operational context beyond them: results are cached with a 2-minute staleness window, each call costs $0.005, and payment is via x402 (USDC on Base or Solana). It does not explain payment failure behavior or whether a cached response is billed, but the cost/latency disclosure is substantive and goes well past the annotations.

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 sentences, front-loaded with the metric list, then freshness and cost. The opening clause largely restates the title verbatim, which is a small redundancy, but no other sentence is padding — each adds data scope, cache window, or pricing.

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?

No output schema exists, so the description carries the burden of describing return contents — and it does, enumerating every returned metric including the 'top 5' cardinality. Cost, payment rail, and cache TTL are covered; what is missing is payment-failure or error behavior and any guidance on the optional `tx` parameter.

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?

With one parameter at 100% schema description coverage, the schema already explains that `tx` is an alternative to the X-Payment-Tx header. The description mentions the x402 payment path but never references the `tx` parameter or when an agent would pass it instead of using the header, so it adds only indirect meaning.

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 (crypto market overview) and enumerates the exact metrics returned: Fear & Greed today/yesterday, total market cap and volume, BTC/ETH dominance, 24h change, and top 5 gainers/losers. The scoping to 'liquid Binance USDT pairs' further distinguishes it from siblings like price, prices, and tokens_trending, which return individual or trending token data rather than a market aggregate.

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 by the metric enumeration — an agent can infer this is a one-shot market-context snapshot — and the 'Cached 2 min' note hints at acceptable freshness. However, no sibling is named as an alternative (e.g., use tokens_trending for broader mover lists, price for a single token), and there is no explicit when-not-to-use guidance despite a crowded sibling set.

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