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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the safety profile is covered. The description adds useful context by naming the data source (Yahoo Finance via yfinance), noting that no API key is required, and explaining the default behavior when expiry_date is omitted. It does not cover rate limits or error behavior, but those are less critical for a read-only, idempotent 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?

The description is compact, well-organized, and front-loaded with the core purpose before the usage bullets. Every sentence adds value: the first sentence defines the action, the second lists outputs, the bullets give when-to-use guidance, and the final lines provide prerequisite and data-source context without filler.

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, idempotent tool with an output schema and clear annotations, the description covers the main practical needs: what it returns, when to use it, how to get valid expiry dates, and what happens if expiry_date is omitted. The only notable omission is explicit guidance on how symbol is required or resolved, and the unrelated generic params are not clarified in the description.

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 reported as 0%, so the description must compensate. It does add meaningful behavior for expiry_date by explaining omitting it returns the nearest expiry, and it implies symbol through 'stock or ETF.' However, it does not explicitly describe the symbol parameter or explain the generic params object and its many fields, leaving a noticeable gap for an agent deciding what to pass.

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 immediately states the exact operation: fetch the full options chain (calls and puts) for one expiry date, and enumerates the returned fields. This clearly distinguishes it from sibling tools like GetOptionsExpirations, which only provides expiry dates, and from other market-data tools. The repeated phrase 'full options chain' plus the specific field list leaves no ambiguity about what the tool does.

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 gives explicit use cases with a 'Use this tool when' bullet list and names GetOptionsExpirations as a prerequisite, which is strong contextual routing. It does not explicitly state when not to use this tool or name alternative tools for related tasks, so it falls just 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.