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

Beyond the readOnly/openWorld annotations it discloses pricing ($0.005 per call via x402, USDC on Base), that Base errors are not charged while other rails may be, the 5-minute cache cadence, the CoinGecko-to-Coinbase fallback source, and the 400 on a bad symbol. It even explains the null-macd edge case for too-few candles, which is real behavioral context an agent cannot get from 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?

It is front-loaded with the payload contents and return shape before moving to pricing and terms, which is the right order. The closing legal/terms sentence and the double disclaimer ('not a forecast and not financial advice') add bulk that an agent does not need for selection or invocation.

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 output schema, the description carries return-value documentation itself and does so well (field list, null semantics, data sources, freshness, error behavior, cost). The one real hole is the symbol parameter that exists in prose but not in the input schema, leaving invocation ambiguous.

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 schema declares zero properties yet the description introduces 'one coin via symbol=' and its 400 failure mode, so the semantics it supplies do not match any declared parameter. The documented meaning of symbol= is useful, but the schema/description mismatch means an agent cannot tell how to actually pass it.

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 the exact resource (precomputed RSI-14, MACD, Bollinger Bands plus OKX perp funding), the covered assets (BTC, ETH, SOL) and the single-coin variant, then enumerates the returned JSON keys. An agent can distinguish this from siblings like funding, funding_report and market_quote purely from the text.

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 use conditions: no candle fetching needed, data refreshes roughly every 5 minutes so repeat calls return identical values, and it is descriptive only, not a forecast. It never names an alternative sibling or an explicit when-not condition, so routing between this and the dedicated funding tools is left to inference.

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