get_zero_dte

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

With no annotations, the description carries the full behavioral burden and handles it well: it notes the Pro plan requirement, the fallback to the nearest expiration, the 'pinRisk n/a' behavior, and explicitly says the tool 'never fakes a pin.' This is far beyond a generic mutation/read hint.

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, then gives prerequisites, parameter semantics, and return shape in compact labeled sections. The market-behavior sentence earns its place by explaining why the 0DTE view matters.

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?

For a single-parameter tool with no output schema, this is complete: it covers access requirements, input semantics, response fields, and edge-case fallback behavior. An agent can select and invoke it correctly without further inference.

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?

Despite 0% schema coverage, the description fully documents the only parameter: 'symbol: Underlying ticker (index/ETF names like SPY/QQQ have daily expiries; most single names do not).' This adds selection guidance that the input schema alone cannot convey.

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 '0DTE focus panel' and states it 'isolates only today's expiring contracts and computes their GEX, gamma flip, max pain, expected move and a pin-risk read.' This is a specific verb-plus-resource statement that sets it apart from siblings like get_max_pain or get_gex_intraday by its expiration-day scope.

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?

It provides clear context for when this tool is relevant ('On an expiration day, that day's dealer gamma dominates the intraday tape') and explains what happens when no true 0DTE exists. However, it does not explicitly name alternatives or state when-not-to-use, so it stops short of full guidance.

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