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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive, so the safety profile is covered. The description adds value beyond them by naming the data source (Yahoo Finance via yfinance) and noting no API key is required, which tells the agent there's no auth setup and the data is third-party. It could go one step further on behavior for an invalid or non-optionable ticker, hence a 4 rather than 5.

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 core instruction and the sequencing dependency are front-loaded in the first two sentences, with bullets used for scannable secondary conditions. Slightly padded by the two when-to-use bullets that largely restate the opening sentence, but nothing is confusing.

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?

An output schema exists, so return values needn't be explained, and the read-only annotations plus the stated data source make the tool's behavior predictable. The only meaningful gap is which parameter to supply, which the description leaves implicit.

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 at 0% for the top-level parameter, so the description must carry weight; it does signal the one meaningful input ('for a ticker') but never names the symbol field or gives format guidance. The bundled plumbing parameters (mcp_prompt_id, wholesaler_ids, source_resource_id, etc.) are not addressed at all, so the description does not compensate for the coverage gap.

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?

A specific verb (list) plus a precise resource (options expiry dates) and scope (for a ticker). It also explicitly distinguishes itself from the sibling GetOptionsChain, so an agent can route between the two without opening either schema.

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 states the sequencing rule directly ('Use this before calling GetOptionsChain to find a valid expiry date') and reinforces it with two concrete when-to-use bullets. No condition is left to inference.

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