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

Annotations already declare readOnly/idempotent/openWorld/non-destructive, and the description adds real value beyond them: exact price ($0.02), two auth paths (Bearer credits key or x402 USDC), that the hub returns payment terms, and that failures are not charged (credits refunded, x402 settles only on success). That is genuinely useful behavioral context for a paid tool. It loses a point for leaving the GET/POST framing ambiguous without clarifying that both are equivalent non-mutating calls.

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 short, but the lead sentence is a cryptic fragment that spends the most valuable position on transport trivia instead of purpose. The pricing block is dense but necessary; the front-loading is effectively inverted, pushing the useful example and terms ahead of any statement of what the tool returns.

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 10 parameters, no output schema, and a tool that computes position sizing, the description says nothing about what comes back (stop distance, units, notional, leverage) — yet account_usd is documented as 'enables units, notional, leverage,' so the agent must guess at response shape. Payment mechanics are covered thoroughly; the actual analytic contract is not.

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 coverage is 100%, so every parameter (bars, stop, stop_atr, entry, tier, risk_pct, etc.) is already documented with defaults and enums. The worked example payload illustrates a realistic call shape but adds no semantics the schema doesn't already carry, so baseline 3 applies.

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 body never states what the tool does — no verb, no resource, no stated output. The opening "Same as GET, POST {...}" is a transport/calling note, not a purpose statement; only the title ('Risk metrics and position sizing') conveys intent, and that is structured metadata rather than description content. Nothing distinguishes it from ta_bias, ta_backtest, check_perp_order, or perp_positioning.

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 only guidance is a billing precondition: 'No free tier (paid route only),' which does tell an agent to prepare a key but says nothing about when to choose this over ta_bias, ta_backtest, or perp_positioning. No exclusions, no prerequisites about data availability, no indication of what input combinations make sense.

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