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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so safety and determinism are covered and the description need not repeat them. The description does add real value by disclosing the calculation authority (Kemenag), which implies results may differ from other Hijri implementations. However, with no output schema, the description never says what comes back — a formatted Hijri string, month name, or structured fields — which is the main behavioral gap.

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?

One short, front-loaded sentence with the resource and the calendar authority placed early and no filler. It is efficient, though its brevity contributes to the direction ambiguity rather than resolving it.

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 tool with no output schema, the description should explain the return value, and it does not. Combined with the unresolved one-way vs two-way ambiguity against its own title and the missing differentiation from hijriah_kalender, an agent has more open questions than the two-sentence definition answers.

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 the single parameter already documents the YYYY-MM-DD Gregorian format, so the baseline is 3. The description adds no format examples, no date-range limits, and no statement about timezone or whether partial dates are accepted, so it does not exceed what the schema already provides.

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 names a specific verb (convert) and resource (Gregorian date to Hijriah) and pins the convention to Kalender Hijriah Indonesia / Kemenag, which is genuinely distinguishing in a domain where Hijri dates can vary by a day. It falls short of 5 because the title advertises bidirectional conversion ('Gregorian and Hijri dates') while the description and the single Gregorian-typed parameter describe only one direction, leaving the agent to guess whether the inverse is supported.

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 guidance and no reference to the sibling hijriah_kalender, which an agent could easily confuse with this tool. The description states only what the tool does, not when to pick it over the calendar-listing sibling or what input preconditions apply.

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