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

Annotations already declare readOnlyHint/idempotentHint/non-destructive, so the safety profile is covered; the description adds the data source (Yahoo Finance via yfinance, no API key) and the fallback behavior for a missing expiry. It does not mention rate limits, data freshness, or chain size, which keeps it short of a 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?

Front-loaded with the core action, then a tight bulleted usage list, prerequisites, and default behavior. No sentence is filler and the structure makes scanning trivial.

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-value detail is not strictly required, and the description still names the key fields. The remaining gap is the unexplained extraneous schema parameters, which an agent could stumble over; otherwise the definition is sufficient for correct invocation.

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?

The description adds real meaning for expiry_date (format expectation via the prerequisite call, nearest-expiry default), but the schema surfaces several additional parameters (wholesaler_ids, exclude_fillers, source_resource_id, additional_display_fields) that the description never mentions or reconciles. With schema coverage reported at 0% and unaddressed parameters, this is adequate but incomplete.

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?

States a specific verb and resource ('Fetch the full options chain (calls and puts) for one expiry date') and enumerates the returned fields (strike, bid, ask, IV, open interest, volume). It is clearly distinguishable from the sibling GetOptionsExpirations, which it explicitly routes to.

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?

Provides an explicit 'Use this tool when' list covering three concrete scenarios (options strategy research, IV across strikes, open interest sentiment), states the prerequisite ('Call GetOptionsExpirations first'), and documents the default case when expiry_date is omitted.

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