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

Annotations already establish read-only, idempotent, non-destructive behavior, and the description adds meaningful constraints: finished sessions only, one day per call, and the deliberate absence of buy/sell signals. It also clarifies the tool returns a holistic measurement bundle rather than a signal or opinion. This exceeds what annotations alone would tell the agent.

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 a dense but readable list of contents, then structured into 'Use when', 'Not for', and 'Limits' sections, each sentence serving a distinct purpose. There is slight redundancy between 'ONE finished SPX session' and 'finished sessions only, one day per call', but it is used to reinforce a key constraint. No filler or irrelevant detail.

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?

With an output schema present and full parameter schema coverage, the description covers the essential invocation context: what is included, when to choose it, which alternatives to use, and the tool's explicit non-signal stance. It also points the agent to the required input domain (finished trading days). Nothing an agent needs to correctly select and call this tool is missing.

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 schema already fully documents the single required `day` parameter with pattern, example, and error behavior for invalid days (100% coverage), so the description doesn't need to add much. The description's 'finished sessions only, one day per call' reinforces the parameter's semantics but does not add new syntax or formatting detail. Baseline 3 is appropriate because the schema carries the load.

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 names a specific verb and resource ('Everything FirmTape measured for ONE finished SPX session') and enumerates the included data (OHLC, VWAP, gamma flip, walls, hold band, net-gamma percentile, ATM IV). It explicitly differentiates from siblings by naming get_levels, get_level_history, and get_gex_profile as different scopes. This leaves no ambiguity about what this tool returns.

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 gives an explicit 'Use when: you want a whole day in a single call' and a 'Not for' list naming the exact alternative tools for each different need. It also states limits (finished sessions only, one day per call) so an agent can decide when to invoke it. No relevant usage condition is left to inference.

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