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

Annotations already declare readOnly, idempotent and closed-world, so safety is covered. The description adds genuine domain facts beyond the annotations (9.75% Saudi rate, 2% expat rate, SAR 45,000 cap, July 2026 phased rate), but it never states what the response contains (monthly total? employee vs employer split?).

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?

It is a single compact sentence, but it leads with a numeric example rather than a statement of purpose, and the trailing URL is low-value for tool selection. The key framing is buried in the middle clause about the July 2026 rate.

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 should describe the shape of the result; the worked example hints at a monthly contribution figure but not whether it is the total, the employee share, or both, and the SAR 45,000 cap's effect on the result is unstated.

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 baseline is 3. The description nonetheless adds interpretive value by supplying the actual rate values behind the 'nationality' and 'phase' enums (2% for non-Saudis, phased rate through 2028) and the cap that applies to the wage.

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 anchors the tool with a concrete worked example ('SAR 12,500 basic + housing costs a Saudi SAR 1,218.75 a month in GOSI (9.75%)'), which makes it obvious this computes Saudi GOSI contributions. It does not explicitly name what distinguishes it from near-neighbours like saudi_end_of_service_calculator, so it falls 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 / when-not-to-use statement and no named alternative. The mention of the new-entrant rate and expat rate implies the domain without telling the agent which scenario selects this tool over the sibling social-insurance calculators.

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