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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds the 7-shift cap and clarifies that the overtime split is arithmetic only, but that caveat largely duplicates the schema's own overtime description, so the incremental value is modest.

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?

A single front-loaded sentence that states the primary action first and the optional behavior second, with no filler. Nothing could be removed without losing meaning.

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 an output schema present, the return values need not be explained, and the description covers the input scope and the overtime option. It is complete enough to call correctly, though a note on how invalid or overnight-crossing times are handled would add polish.

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%, so rows, start/end, breakMinutes, overnight and overtime are all already documented in the schema. The description adds the 40-hour threshold concept but no format, ordering, or edge-case semantics beyond it, which matches the baseline 3 for a fully-documented 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 names a specific verb and resource (sum clock-time shifts) and states the cardinality cap (up to seven), so the tool's function is unambiguous. It does not differentiate itself from nearby siblings such as hours_calculator, so it stops 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?

There is no when-to-use or when-not-to-use guidance, and no alternative is named even though hours_calculator sits adjacent and can plausibly be confused with this one. The reader must infer the use case from the description alone.

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