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

With annotations already declaring readOnlyHint=true and idempotentHint=true, the description adds some behavior: it returns both prices from one input. However, it does not disclose what happens if both call and put are provided, or neither – a significant edge case given that neither is required in the schema. This leaves room for interpretation.

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 two sentences, front-loaded with the concept name and immediate purpose. Every word earns its place, and it avoids restating schema fields. This is an example of high-efficiency writing.

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?

Given the output schema exists, return values need not be explained. The description covers the core behavior and inputs, but it lacks the crucial constraint that exactly one option price must be provided. This is a functional prerequisite that would affect an agent's invocation, so the description is adequate but not complete.

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 baseline is 3. The description does add the meaning that only one of call/put needs to be provided, which is useful context beyond individual field descriptions. However, it does not go into detail about units, defaults, or the dividend yield parameter, which are already covered by the schema.

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 identifies the tool as implementing put-call parity and states its function: 'given one option price, returns both.' This is a specific verb+resource+scope, and the name itself distinguishes it from siblings like black-scholes or option-greeks.

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?

It explicitly tells the user when to use it: 'given one option price' – i.e., when you have one option price and need the other. It also lists the required inputs ('Provide call or put, plus spot, strike, years, and the rate'), giving clear context. However, it does not explicitly name alternatives or state when NOT to use it, falling 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.