stock_options_chain

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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds valuable behavioral detail beyond the schema: it returns the nearest expiry when none is provided, errors with a list of valid expiries if the given one doesn't match, and fully documents the return structure including underlying prices, counts, and per-strike fields. This gives an agent a clear picture of side effects, error behavior, and output shape.

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 one-sentence summary, explicit usage triggers, and then precisely formatted Args and Returns sections. Every sentence earns its place, and the length is justified by the need to document both parameters and the full return shape without an output schema.

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?

Given no output schema, the description thoroughly documents the return payload, including nested call/put objects with all key fields. It covers required behavior (nearest expiry, error on invalid expiry), parameter semantics, and the distinction between calls and puts. An agent has everything it needs to invoke this tool correctly and interpret the result.

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 carries full parameter-documentation weight. It defines `symbol` with concrete examples ('AAPL, NVDA, TSLA, SPY') and `expiry` with format constraints, validity rules, and error behavior. This exceeds what a bare schema would provide and leaves no ambiguity about how to populate each argument.

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 clearly states the tool's role: 'Full options chain (calls + puts) for a US stock symbol and one expiry.' It uses a specific verb ('returns,' 'Use this when') and identifies the exact resource, distinguishing it from generic quote tools like yahoo_price or stock_prices. The examples ('show me AAPL puts expiring next Friday') make the intent unmistakable.

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 provides explicit trigger phrases: 'Use this when the user asks...' and gives concrete examples. It also explains the no-expiry fallback behavior and invalid-expiry error handling. However, it does not explicitly name sibling alternatives or state when NOT to use this tool versus stock_options_unusual_activity or other option-related tools.

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