option_expirations

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

With no annotations, the description carries the burden and does add a behavioral filter: only expirations 'with listed contracts' are returned, and the result is scoped to a single underlying. However, it does not disclose output format, ordering, or any time-related behavior, which are left to inference.

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?

One short sentence, front-loaded with the core payload and ending with the intended use. No filler or repetition.

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 one-parameter read-style tool with no output schema, the description provides the essential context: what is returned and how the result feeds into option_chain. Minor missing details like date formatting or sort order are not critical for selecting and invoking this tool.

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 0%, so the description must compensate. '...for one underlying' maps the symbol parameter to the underlying asset, but it adds no detail on ticker format, casing, or how symbol is validated. For a single obvious parameter this is adequate but minimal.

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 indicates the tool provides expiry dates that have listed contracts for one underlying, which distinguishes it from the option_chain sibling by framing this as the precursor step. It lacks an explicit action verb like 'lists' or 'returns,' but the intent is unambiguous.

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?

'Pick one for option_chain' explicitly tells an agent when to invoke this tool: before requesting an option chain, use this to choose an expiration. It gives clear context but does not mention exclusions or alternative tools beyond the implied downstream relationship.

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