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

The description explains the output format as a decimal (e.g., 0.07 = 7%), which is valuable behavioral context beyond the annotations that declare read-only and idempotent behavior. It does not cover edge cases or side effects, but for a simple calculation this adds sufficient transparency.

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 a single sentence that defines the tool and includes the return format. It is front-loaded and contains no waste, perfectly balancing brevity and informativeness.

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 simple calculation tool with annotations and an output schema, the description is complete enough. It states the purpose and the output format, though it does not address potential edge cases (e.g., zero starting value) or parameter constraints, leaving a minor gap.

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 already provides descriptions for all three parameters (begin, end, years) with 100% coverage. The description adds no new parameter-specific meaning beyond 'between two values... over a number of years', which is a restatement rather than additional semantic detail.

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 defines the tool as computing the compound annual growth rate between two values over a number of years. This includes the specific verb 'growth rate' and the resources/parameters involved, distinguishing it from other financial calculators.

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 implies when to use the tool (when a CAGR calculation is needed) but does not provide explicit guidance on alternatives or exclusions. It lacks a 'when not to use' statement or references to sibling tools, so it only meets the implied usage level.

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