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

Annotations provide no positive hints (all false), so the description carries the burden. It discloses the calculation formula, the possibility of half days, and the rounding-down behavior on the report. This goes well beyond the structured fields, though it could mention whether any side effects or permissions apply.

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 two concise sentences with no filler. It front-loads the main action and resource, then gives the formula and rounding behavior efficiently.

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 single-parameter tool with no output schema, the description adequately explains what is computed and what the output looks like. It is missing minor details like error handling for unknown employees, but that is not critical for a simple balance lookup.

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 already explains that 'employee' is an id or name. The tool description adds no further parameter-level meaning, so it meets the baseline but does not exceed it.

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 states a specific verb ('Show') and a specific resource ('one employee's leave balance'), and it details exactly what the balance consists of. It is clear and distinct from the sibling tools, though it does not explicitly name an alternative tool for comparison.

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 intended use is implied by the description: use this when you need a single employee's leave balance. However, it does not explicitly state when not to use it or point to an alternative such as leave_list.

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