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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds real behavioral context beyond that: the annual-leave-only constraint, the 100-employee ceiling, and the underlying endpoint for provenance. It stops short of describing pagination semantics or what a balance summary contains, but that is a minor omission given the annotation coverage.

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?

Three tight sentences: resource scope first, constraint second, endpoint last. Nothing is redundant or buried, and the most important limitation (annual leave only) is front-loaded.

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 zero-required-param, read-only list tool with full schema coverage and no output schema, the definition supplies everything needed to call it correctly. The one gap is that 'balance summaries' is not unpacked, so an agent cannot anticipate the returned fields.

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%, so the schema already documents page, limit, and employee_codes thoroughly. The description's 'at most 100' and 'omit for everyone' restate what maxItems and the property descriptions already encode. Baseline 3 is correct when the schema does all the work.

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 resource (annual leave balances), unit of return (per employee), and scope (all employees or a subset of employee codes). The endpoint path and the explicit note that only the annual leave type is supported make the domain unambiguous relative to other leave-related siblings.

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?

Gives clear conditions: omit employee_codes to get everyone, supply codes for a subset, at most 100. The line 'Only the annual leave type is supported by Jisr' scopes expectations. It never names an alternative call (e.g. accrual transactions) for other leave types, but the surrounding context is clear enough.

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