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

Annotations already declare readOnlyHint=true and idempotentHint=true, and the description adds the concrete outputs (upfront cost, monthly saving, months to recoup). This provides meaningful context beyond the structured fields, and there is no contradiction with annotations.

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 front-loads the tool's purpose and lists its outputs. Every word is informative, with no redundancy or tangential information.

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?

Given a well-documented 5-parameter schema, an output schema, and clear annotations, the description adds the essential concept of what the tool returns. The tool is a straightforward calculator, and the information provided is sufficient for correct use.

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?

All 5 parameters are fully described in the schema (100% coverage), so the baseline applies. The description conceptually links parameters to outputs (e.g., upfront cost from pointsPct and loanAmount) but adds no individual parameter details beyond the schema.

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 identifies the tool as computing mortgage points break-even, listing the three key outputs: upfront cost, monthly payment saving, and months to recoup. It is specific enough to distinguish from sibling tools like break-even-units (sales units) and refi-breakeven (refinancing).

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 the intended use case (analyzing mortgage points buy-down) but does not explicitly state when to use this tool versus alternatives. Sibling tools like refi-breakeven are visible to the agent, but no direct comparison or exclusion is provided.

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