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

No annotations are provided, so the description carries full transparency. It states the tool is an estimation tool and lists the return fields (doubling_years_rule72, doubling_years_precise, annual_rate_pct), implying it is a pure calculation with no side effects. This is sufficient for a simple financial calculator.

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?

Two sentences, no redundancy. The first sentence defines the purpose, the second enumerates returns and points to related tools. Every word earns its place.

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 a well-understood purpose, the description is complete. It covers what the tool does, what it returns, and where to find similar tools. No gaps remain.

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 input schema covers 100% of parameters, with a clear description for annual_rate. The description does not add information beyond the schema but provides context by mentioning the rule and return fields. Baseline 3 is appropriate as the schema already handles parameter documentation.

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 the tool's purpose: 'Estimate years to double an investment using the Rule of 72.' It specifies the verb (estimate), resource (years to double an investment), and the method (Rule of 72). It also mentions return fields and related calculators, distinguishing it from siblings like calculate_compound_interest.

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 provides a clear context: it is for estimating doubling time using the Rule of 72. It directs users to list_bundles for related 'finance-universal' calculators, offering guidance on where to find alternative tools. However, it does not explicitly state when not to use this tool versus more complex financial calculators.

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