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

Annotations already carry the safety profile (readOnlyHint=true, idempotentHint=true, destructiveHint=false), so the description needs only additive context. It adds valuable provenance and auth information: 'Source: Yahoo Finance via yfinance. No API key required.' No contradiction with annotations.

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 purpose is front-loaded in the first sentence, and the whole text is compact. Minor redundancy: the second bullet ('You need a specific expiry date to pass into GetOptionsChain') largely restates the preceding sentence, so not every sentence earns its place.

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 and annotations are rich, so return-value and safety explanations are not required. The description covers purpose, usage, source, and auth adequately for a simple read-only listing tool. However, it never reconciles the oddly generic internal parameters (wholesaler_ids, exclude_fillers, source_resource_id) with the Yahoo Finance data source, which may confuse an agent deciding what to populate.

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 compensate, but it only loosely implies the symbol parameter via 'for a ticker'. None of the other schema fields (mcp_prompt_id, question_asked, wholesaler_ids, exclude_fillers, source_resource_id) are addressed, leaving the agent with no guidance about which parameters matter for a Yahoo Finance options-listing call. The description does not bridge the gap left by the low-coverage schema.

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 states a specific verb and resource — 'List all available options expiry dates for a ticker' — and immediately differentiates itself from the sibling GetOptionsChain by establishing that this tool is the prerequisite step for finding a valid expiry date. An agent can distinguish it from GetOptionsChain without inspecting 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?

Explicit 'Use this tool when' bullets give concrete trigger conditions (know which contracts exist for a stock/ETF; need an expiry to pass into GetOptionsChain) and name the downstream sibling. It lacks an explicit when-not-to-use clause, so it stops just short of fully explicit routing.

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