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

With no annotations, the description carries the full burden, and it does so thoroughly. It discloses deterministic arithmetic, no market-data dependency, the OCC $0.01 rule, account-type restrictions, margin requirements, trap-zone behavior, and pin risk, giving an agent a strong behavioral model before invocation.

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 every clause earns its place, front-loading the core purpose before moving into details. It is appropriately sized for an 11-parameter tool with no output schema, and it avoids repeating the schema.

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 tool with no output schema, the description covers most needed context: inputs, key rules, account constraints, risk scenarios, and deterministic behavior. The main gap is that it does not explicitly describe the return shape or how edge cases like OTM outcomes are presented, but the described scope is otherwise strong.

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 82%, so the baseline is 3. The description adds meaningful semantics beyond the schema by explaining account-type restrictions (margin, cash, IRA), the expected-move test, and the OCC auto-exercise threshold, which helps the agent reason about parameter choices without reading the schema alone.

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 clearly explains what the tool does: it models what happens when a single-leg US equity option is in the money at expiration, covering auto-exercise, resulting share positions, account constraints, P&L, break-even, trap zone, and pin risk. It is specific about the resource (option expiry outcomes) and distinguishes itself from the unrelated financial-planning sibling tools.

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 description makes the intended use clear: test expiration outcomes for a single-leg US equity option and optionally add an expected move. It does not explicitly name alternatives or say when not to use it, but the sibling tools are unrelated and the usage context is unmistakable.

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