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

With no annotations, the description carries the full burden. It discloses the calculation window (rolling 5-min) and asset set, and clarifies it is not a trigger. However, it does not mention what the output represents, how many data points are included, or any limitations; some of this is likely covered by the output schema.

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 two short sentences with no filler. The core metric and asset list are front-loaded, and the usage caveat is immediate and memorable.

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 zero-parameter tool with an output schema present, the description provides sufficient context: the metric, the assets, and the intended role. It could add a bit more about how to interpret the correlation grid or when to favor it over sibling correlation tools, but the essentials are covered.

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 tool has zero parameters, so there is no parameter semantics burden. The baseline of 4 applies, and the description adds useful context about the assets and rolling return methodology even though no parameters need explanation.

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 a specific metric (rolling 5-min return correlation) and the exact resources (SPY/QQQ/IWM/DIA). It also positions the tool as a portfolio overlay rather than a signal trigger, which separates it from alert-style siblings, though it does not name a specific alternative.

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?

"Portfolio overlay, not a trigger" gives clear guidance on when to use it: as background context for portfolio assessment, not as an entry/exit trigger. It provides a useful exclusion but stops short of naming alternatives or explicit when-to-use conditions.

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