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

Annotations already indicate read-only ('readOnlyHint': true). The description adds behavioral context: dates are calendar positions (not sighting announcements) and defaults to today. No contradictions.

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?

Two sentences with no extraneous information. First sentence captures the core function, second sentence covers input options and a key clarification. Efficient and well-structured.

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 no output schema, the description covers input modes, defaults, and nature of dates. It is complete enough for a calendar tool, though it could mention that output includes a list of days with significance notes.

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 parameters are well-documented. The description adds relational meaning: one can use either (year+month) or (date) or none, and clarifies default behavior, which goes beyond the schema's individual descriptions.

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 clearly states the tool gets a full Hijri month mapped to Gregorian dates with significant days, using specific verbs 'Get' and 'mapped'. It distinguishes from sibling tools like 'get_hijri_date' by emphasizing the full month and significant days.

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 description explains two input modes (Hijri year/month or Gregorian date) and notes defaults and nuances (dates are calendar positions). However, it does not explicitly compare to siblings or state when not to use this tool.

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