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

Annotations already cover safety (readOnly, idempotent, non-destructive, openWorld), but the description adds hard-to-find context: per-call cost ($0.005 via x402, USDC on Base, MCP payments Base-only), that errors are not charged, null semantics for macd on thin candles, data source fallback chain, and the ~5-min refresh window. That is substantive behavior far beyond structured hints.

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?

Front-loaded with purpose and usage, then progressively adds cost, freshness, and return-shape details; every sentence carries operational value. It is densely packed into long compound sentences, which slightly hurts scannability for an agent parsing it quickly.

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, yet the description enumerates the return keys (rsi14, macd{macd,signal,histogram}, bollinger{upper,middle,lower,period}, lastClose, fundingRate/fundingTime) and their null cases. Combined with cost, freshness, and sourcing, nothing needed to call and interpret the tool is missing.

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 with 100% schema coverage, so the baseline is 4. The description reinforces this with 'Call GET with no parameters', leaving no ambiguity about invocation, but there is nothing further parameter-wise to clarify.

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?

Opens with a specific resource and the exact indicators returned (RSI, MACD, Bollinger), then scopes it to BTC/ETH/SOL. It explicitly distinguishes itself from price-oriented siblings with 'rather than just prices', so an agent can route between this and market_quote/funding without opening a schema.

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?

States exactly when to use it ('when you need indicators... rather than just prices'), how to invoke it ('Call GET with no parameters'), and adds a cadence constraint tied to data freshness ('changes about every 5 min; calling more often returns the same values'). This is explicit when-to-use guidance with the sensible alternative named.

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