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

With no annotations, the description carries the full burden. It usefully discloses that this is a paid endpoint ($0.003 per call via x402/MPP) and the transport (POST /api/iran/iran_holiday_check), which is genuinely valuable operational context. It says nothing about rate limits, error behavior for malformed dates, timezone handling, or whether a non-holiday date returns a negative flag or an error.

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 entry is dominated by boilerplate metadata (Origin URL, origin hostname, brand, provider aliases, family key, endpoint) while the actually useful sentence is repeated verbatim under both 'Summary' and 'Source description'. The functional content is not front-loaded and the payload is roughly 80% infrastructure noise.

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 simple three-parameter read-only tool, the definition covers auth mode, price, endpoint, calendar system, and example uses, which is the minimum an agent needs to invoke it. It remains incomplete on the return shape ('name it if so' is vague) and on invalid-date handling, and there is no output schema to fill that gap.

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 0% across all three required numeric params (year, month, day), so the description must compensate. It does clarify the one ambiguity that matters most by specifying these are Gregorian date components rather than Jalali, but it adds no ranges, validation rules, or format guidance, leaving the rest undocumented.

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 functional summary states a specific verb and resource: check whether a Gregorian date is an Iranian public holiday and name it. That is clear and actionable, but the definition never distinguishes itself from the near-identical sibling iran_holidays, nor from business_days or gregorian_to_jalali, leaving overlap unresolved.

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 'Use case' and 'Keyword' lines imply when the tool applies (e.g. checking the status of 2026-03-21), which is better than nothing. However, there is no explicit when-to-use vs the sibling iran_holidays, no statement about valid date ranges, and no exclusions, so selection between the two holiday tools remains a guess.

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