Historical Options Chain

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

Annotations already declare readOnlyHint=true. The description goes beyond that by explaining this is an EOD snapshot with multi-year historical availability, which clarifies the temporal behavior. It could add more details about data caveats (e.g., splits/dividends), but it is transparent enough for safe 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 well-structured and front-loaded: a crisp definition, then use guidance, then args, then return summary. Every line adds value and there is no filler or redundant restating of the title.

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 read-only tool with three simple string parameters and no output schema, the description covers purpose, usage, parameters, and return type. It stops short of describing the exact shape of the chain snapshot, but the provided context is sufficient for selecting and invoking the tool correctly.

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 0%, so the description must carry the burden. It does so by listing each parameter with a semantic hint and date format ('Stock symbol', 'Expiration date YYYY-MM-DD', 'The historical date to snapshot YYYY-MM-DD'). No enums or nesting, so this is adequate.

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 uses a specific verb phrase ('Get the options chain as it looked on a past trading day') and clearly identifies the resource (historical options chain). It distinguishes itself from the current-chain sibling by emphasizing the historical EOD snapshot nature.

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 'Use this tool when the user asks about' and provides concrete use cases like historical pricing, pre/post-event chain views, and backtesting. These exclusions help an agent select it over current-chain or other options tools.

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