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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, and closed-world behavior, so the safety profile is covered. The description adds little beyond that (no auth, limits, or edge-case behavior), which is acceptable for a pure calculator but not rich context.

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?

Purpose is front-loaded and the text is short and scannable. However, the 'Inputs:' and 'Returns:' sentences largely duplicate the input schema and the existing output schema, so a small amount of redundancy is present.

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 three-parameter calculator with an output schema and full annotations, the description supplies enough to call it correctly. It also cross-references list_bundles for related finance calculators, adding useful discovery context.

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?

Schema coverage is 100%, so the schema already documents all three parameters with EUR units. The description's 'cash on hand, monthly expenses, monthly revenue' merely restates these inputs without adding syntax or interpretation, matching the baseline 3 for high-coverage schemas.

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?

States a specific verb ('Compute') and resource ('startup monthly burn rate and runway'), which is clearly distinct from neighboring finance calculators like calculate_churn_rate or calculate_break_even. It does not explicitly contrast itself with any sibling, so it stops just short of a 5.

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?

Provides a clear when-to-use statement ('Use for fundraising or expense control'), giving the agent concrete scenarios. It offers no exclusions or named alternatives, which keeps it from a 5.

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