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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It does not state whether the tool returns time-series data, what format, or any limitations, focusing instead on user-oriented activities like 'analyze' and 'study' rather than the tool's actual behavior.

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 sentences with no extraneous words. It front-loads the main action and resource, making it easy to scan.

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 tool is simple, but in the absence of an output schema, the description should explain what the returned data looks like or what kind of historical data is included. It mentions 'changes in composition' and 'performance across periods', which is helpful, but lacks specificity about return structure or data granularity.

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 the input schema is already fully descriptive. According to the rubric, a baseline of 4 is appropriate for zero-parameter tools, and the description does not need to add parameter details.

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?

Clearly states it provides historical data for the Dow Jones Industrial Average, with verbs 'Access' and 'Analyze' that distinguish it from sibling tools covering other indices (e.g., getHistoricalSP500Changes). This is specific and informative.

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?

Implicitly tells when to use it (whenever Dow Jones historical data is needed) and provides clear context for performance and composition analysis. However, it does not explicitly mention alternatives or exclusions, so it falls short of a perfect score.

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