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

Annotations already indicate a safe read-only operation, but the description goes well beyond that. It discloses plan-dependent bid/ask behavior (real-time OPRA on Pro, delayed indicative on Plus, end-of-day with upgrade note on Free), timestamp provenance, separate effective dates for open interest, and the fact that IV/greeks are provider model values computed at fetch time that may differ from chain responses. 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 description is front-loaded with the core purpose and then efficiently enumerates data fields and caveats. It is a single dense paragraph rather than a list, but every clause adds necessary behavioral or plan-specific detail. It could be slightly better organized, but there is no fluff or repetition.

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 there is no output schema, the description carries the full burden of explaining what the agent will receive, and it does so thoroughly: greeks, IV, open interest, latest price, bid/ask, day range, volume, timestamps, effective dates, and plan entitlements. It also addresses data source caveats and upgrade responses. This is enough for an agent to correctly invoke the tool 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?

Both parameters already have full schema descriptions, so baseline is 3. The description adds value by explaining the contract parameter is an OCC symbol and providing a concrete example (O:AAPL260724C00110000), which helps an agent construct valid input. It also reinforces that ticker is the underlying stock through the AAPL example.

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 opens with a specific verb-resource pair: 'Get the full snapshot for ONE option contract by its OCC symbol.' It lists the exact data fields returned and the example OCC symbol, and it clearly differentiates from chain-level tools by emphasizing 'ONE option contract.' This makes the tool's purpose unambiguous and distinct from siblings like GetOptionChain.

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 clearly establishes the use case: fetching a single option contract snapshot by OCC symbol. It does not explicitly name alternatives like GetOptionChain or state when not to use this tool, but the scope is precise enough that an agent can infer the correct context. The plan-based differences (Pro, Plus, Free) also give conditional usage guidance.

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