Human-readable description of a 5-field cron expression plus the next N run times in a given IANA timezone. Cost €0.0005 per call, charged to the API key in Authorization: Bearer. Parameters — expr: cron expression, e.g. '0 9 * * 1-5'; language: en (default) | ru | uk | ua; tz: IANA timezone, default UTC; count: 1–20, default 5.
| Name | Required | Description | Default |
|---|---|---|---|
| tz | No | ||
| expr | No | ||
| count | No | ||
| language | No |
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are supplied, so the description carries the whole burden, and it delivers useful operational facts: a stated price per call (€0.0005) and the required Authorization: Bearer API key. It also discloses defaults (tz UTC, count 5, language en) and the count range 1–20; it stops short of describing error behavior for malformed expressions.
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 tight sentences: capability first, then cost/auth, then a parameter block with defaults and ranges. Every clause carries information and nothing is padded.
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?
With an output schema present, return-value explanation is unnecessary, and the description covers all four parameters, pricing and auth. It would be fully complete with a note on invalid-expression handling, but nothing essential to invoking it correctly is 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 description coverage is 0%, so the description must compensate and largely does: it gives an example expression '0 9 * * 1-5', enumerates language values, and supplies defaults and bounds for tz and count. The gap is minor inconsistency — count is typed as a string in the schema while the description frames it as numeric 1–20, and the 'ua' language value sits oddly beside 'uk'.
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 ('human-readable description of a 5-field cron expression plus the next N run times') and scopes it to an IANA timezone. The combination of cron parsing and upcoming-run listing is distinctive against siblings such as tz_convert or holidays.
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 implied by the purpose — explain a cron expression and preview its schedule — with defaults given for tz and count. However, it never states when to prefer this over alternatives (e.g. tz_convert for offsets) or any exclusions such as non-5-field/quartz expressions.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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