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

The description discloses the exact calculation logic (strike + premium for call, strike - premium for put), which goes beyond the annotations' read-only and idempotent hints. It provides full behavioral transparency for this pure calculation tool.

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?

A single, front-loaded sentence that is efficient and free of wasted words. It immediately states the purpose and formula, making it easy to parse.

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?

The tool is simple, and the description fully covers the calculation logic. With a present output schema and comprehensive parameter definitions, there is no missing context or needed elaboration.

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?

The description adds meaningful relationships between the parameters (type, strike, premium) by explaining how they combine in the formula. This goes beyond the schema's individual parameter descriptions, even though schema coverage is 100%.

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 states the tool's purpose: calculating break-even underlying price at expiry, with explicit formulas for calls and puts. It distinguishes itself from sibling break-even tools (e.g., break-even-units, points-breakeven) by focusing on options.

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 implies usage for option break-even calculations but does not explicitly mention when to use this tool over alternatives or any exclusions. It lacks explicit when/when-not guidance, but the context is clear from the formula and title.

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