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

No annotations are provided, so the description carries the full disclosure burden. It does add one genuinely useful behavioral fact — the $0.002 USDC x402 cost per call — but says nothing about the calculation convention used (Umm al-Qura vs. local moon sighting), timezone handling, or that Hijri dates can vary by region; for a religious calendar tool those differences materially affect results.

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 sentence of substance plus a bracketed price tag, with no filler and the event list doing real work by naming the returned data. The paid-call prefix slightly delays the core verb, which is why it is not a 5.

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?

This is a low-complexity, zero-required-parameter read tool with a fully documented schema and no output schema; the description covers both capabilities and enumerates the event names an agent can expect back. The remaining gap — conversion basis/timezone and return shape for the conversion path — is modest for a tool of this complexity.

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%, with each of the three optional parameters documented including defaults and an example Hijri format. The description adds no parameter meaning beyond that, so the baseline 3 for high-coverage schemas applies. It also does not clarify precedence when `hijri` and `year` are both given.

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 states a specific pair of operations — Gregorian↔Hijri date conversion and listing the year's Islamic events — and enumerates the events returned, so an agent can tell this is the calendar/Hijri resource rather than prayer_times or qibla. It stops short of explicitly differentiating itself from those neighbouring siblings, which keeps it out of the top band.

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?

Usage is only implied through the schema: pass `date`/`hijri` to convert, or `year` to list events. There is no explicit statement of when to choose this over prayer_times or halal-related siblings, and no note about what happens when both `hijri` and `year` are supplied.

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