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

Annotations already establish readOnly, idempotent, non-destructive behavior, and the description adds important domain-specific caveats: the result is computed, may differ by ±1 day, and has medium data_confidence. It also explains confidence levels and mentions estimated_items and official sources, which is valuable context beyond the annotations.

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 front-loaded with the conversion purpose and remains reasonably efficient. It does enumerate response fields despite having an output schema, which is slightly redundant, but the confidence-level explanation 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?

Given the single required parameter, full schema coverage, annotations, and an output schema, the description covers what an agent needs: the computed nature, confidence semantics, intended uses, and an example. No critical behavioral or contextual information appears missing.

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%, and the schema already documents the single date parameter with ISO format and valid range. The description provides an example input but does not add semantic constraints beyond what the schema already states, so baseline 3 is appropriate.

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: convert a Gregorian date to the Hijri calendar using Umm al-Qura tables. The direction is unambiguous and clearly distinguishes it from the inverse sibling hijri_to_gregorian.

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 positive guidance: use for Hijri-dated documents and to estimate Islamic holidays. It also warns that the official UAE date is set by moon sighting and may differ, implying it should not be treated as authoritative for official dates, but it does not name a specific alternative tool or source.

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