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

Annotations already establish the safe read-only profile, yet the description adds substantial behavioral context: coin-settlement semantics, why a debit vertical's profit is a finite window rather than unbounded, and why an iron condor's loss is genuinely unbounded toward price->0 (maxLossCoin: null). This is exactly the non-obvious domain behavior an agent cannot get from the schema.

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 long, but the scoping sentence is front-loaded and the elaborate middle section is high-value domain caveat rather than filler. Some tightening is possible, but most sentences earn their place for a tool this non-intuitive.

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 returned fields (structureType, netDebitCoin, scenarioPayoffCoin, scenarioPnlCoin/Usd, breakevenPrices, maxLossCoin/maxProfitCoin null semantics, isProfitable). For a complex multi-leg options tool, an agent has everything needed to call and interpret it.

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 all four parameters including the leg shape and currency enum. The description largely mirrors the leg-count constraint and adds the netDebitCoin sign convention, but adds little parameter syntax beyond what the schema provides. Baseline 3 is 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?

States a specific computation (payoff, breakevens, max profit/loss) on a specific resource (Deribit BTC/ETH vertical spread or iron condor/butterfly), and pins the exact leg structure. An agent can distinguish it from run_options_payoff, run_straddle_strangle, and run_spread_reader 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?

Explicitly states when to use it with trigger phrases ('Use when user asks about a bull/bear call/put spread, vertical spread, iron condor...') plus two concrete example queries. No explicit negative routing against sibling payoff tools, which keeps it short of a 5.

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