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

Annotations already declare readOnly, idempotent, non-destructive behavior, so the description is not burdened with safety disclosure. It adds meaningful context beyond annotations: payment of $0.003 USDC per successful x402/Solana call, JSON POST body, and an equivalent HTTPS endpoint. It does not detail failure billing or rate limits, keeping it below 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?

The description is dense but front-loaded with the core purpose and indicator list, followed by output, input, transport, and pricing details. Every sentence adds value, though the final HTTPS endpoint sentence is secondary and could be slightly less prominent.

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?

For a five-parameter paid calculator with no output schema, the description explains the computed indicators, that latest values and optional recent series are returned, and what plain signals mean. It also covers payment and input modes, leaving only exact response structure and error behavior unstated.

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?

Schema description coverage is 100%, so the schema already documents close, candles, period, series, and indicators in detail. The description reinforces the two input modes and notes that some indicators require candles, but adds no syntax or format details beyond the schema, making baseline 3 appropriate.

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 states a specific verb and resource: technical analysis on a supplied price series, and enumerates the exact indicators computed. It is clearly distinguishable from siblings such as macro_indicators or black_scholes because it operates on user-supplied close prices or OHLCV candles.

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 implies usage through 'a price series you supply' and notes that ATR, stochastic, OBV and VWAP need candles, but it does not explicitly say when to use this tool versus alternatives such as macro_indicators or portfolio_metrics. The guidance is present but inferential rather than prescriptive.

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