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

Annotations already cover safety (readOnly, non-destructive, closed-world), so the description is free to add domain behavior — coin settlement, coin-denominated outputs, the USD convenience field, and the counterintuitive capped-call / unbounded-put payoff shape explicitly labeled 'not a bug'. That is exactly the context an agent needs to avoid mis-reading results.

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-loads the core purpose and then layers the important settlement caveat; most sentences earn their place. It is dense and errs long, with the long-call/long-put asymmetry explained in one admittedly run-on sentence.

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 compensates by enumerating the returned fields (intrinsicPerUnitCoin, scenarioPnlCoin, scenarioPnlUsd, breakevenPrice, maxLoss/maxProfitCoin, isProfitable) and the null=unbounded convention, which is everything an agent needs to interpret the response.

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 71%, so the schema documents most inputs itself; the description reinforces that premium/P&L are base-coin denominated and echoes the max-profit formula, but it does not clarify parameters the schema leaves thin (e.g. multi-unit scaling of quantity or the currency default beyond a passing mention). Adds marginal value over the schema, hence baseline 3.

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?

Specific verb and resource: computes payoff, P&L, and breakeven for a single-leg Deribit BTC/ETH option at a scenario expiry price. The 'single-leg' scope cleanly separates it from run_spread_payoff and run_straddle_strangle, so an agent can route without opening the 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?

Gives explicit trigger phrases ('what does my BTC call/put pay off at price X?', 'where's my breakeven on this option?') which is strong when-to-use signal. It never names an alternative tool directly, relying on 'single-leg' to imply the exclusion, so it stops short of full routing guidance.

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