stock_options_chain

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

Despite no annotations, the description fully discloses the tool's behavior: it returns underlying price/change, requested expiry, available expiries, counts, and detailed options data. It also covers error handling for invalid expiry dates.

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 with a concise introductory paragraph followed by clear Args and Returns sections. Every sentence adds value without redundancy.

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?

The description is complete for the tool's complexity: it covers input constraints, output shape (including nested objects), and edge cases (no expiry, invalid expiry). No additional information is needed for correct usage.

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 input schema has no descriptions (0% coverage), but the description adds rich meaning: symbol is described as a US stock symbol with examples, and expiry is explained as an optional ISO date that must match Yahoo's available expiries, including error behavior.

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 explicitly states it returns the full options chain (calls + puts) for a US stock symbol and one expiry. It differentiates from siblings by focusing on the complete chain for a given expiry, and even clarifies behavior when no expiry is provided.

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 clear usage examples ('what's the options chain for X?', 'show me AAPL puts expiring next Friday', etc.) and explains the fallback behavior when no expiry is given. It implicitly contrasts with siblings like unusual activity tools.

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