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

Annotations already declare readOnlyHint=true and idempotentHint=true, covering the safety profile. The description adds the concrete output details (amount off and final price), which are not revealed by annotations or schema alone, giving useful behavioral transparency for a calculation tool.

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, front-loaded sentence that conveys the tool's purpose and outputs without any wasted words. Every phrase contributes meaning, achieving excellent conciseness.

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 two-parameter financial calculator, the description covers the essential purpose and outputs. The presence of an output schema (though not shown) reduces the need to detail return values. It misses edge-case handling (e.g., percent as fraction vs. whole), but this is not a critical gap for such a tool.

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% (price and discountPct both have descriptions). The description does not add any further parameter-specific meaning, but since the schema fully documents the parameters, a baseline of 3 is appropriate.

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 explicitly states the tool computes a single percentage discount and reports both the amount off and the final price. The word 'single' distinguishes it from the sibling tool 'successive-discounts', making its purpose unambiguous.

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 clearly implies use for one discount rather than multiple/layered discounts. It does not explicitly name an alternative tool (e.g., successive-discounts), but the 'single' qualifier provides contextual guidance without excluding edge cases.

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