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

Annotations cover the safety profile (readOnly, non-destructive, closed-world), so the bar is lower. The description adds real behavioral value beyond them by disclosing that it returns two values (remainder AND floored quotient) and that it uses floored rather than truncated semantics, which materially changes results for negative operands.

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 short sentences, front-loaded with the core action and with zero filler. Every clause 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?

With no output schema, the description correctly names both returned values (remainder and floored quotient), which is exactly what an agent needs here. It does not spell out negative-operand behavior or the divisor-zero case beyond the schema's 'not zero' constraint, leaving a small 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?

Schema description coverage is 100% and the schema already documents 'Dividend' and 'Divisor, not zero'. The description adds only the decimal-input scope note, which mildly extends the schema's number-typed parameters. Baseline 3 applies.

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 and resource: compute the remainder and floored quotient of a division. It clearly separates itself from the surrounding calculator siblings (interest, mortgage, BMI, etc.), none of which overlap. No explicit sibling differentiation is needed because none competes.

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?

There is no when-to-use/when-not statement, but the scope note 'works for decimal inputs, not just integers' implies the tool is usable beyond integer modulo cases an agent might otherwise reach for. Usage is only implied, not stated with alternatives.

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