Parse a cron expression into a human-readable schedule description. Supports standard 5-field cron (minute hour day month weekday).
| Name | Required | Description | Default |
|---|---|---|---|
| expression | Yes | Cron expression (e.g., "0 9 * * 1-5", "*/15 * * * *") |
| Name | Required | Description | Default |
|---|---|---|---|
| fields | No | ||
| expression | No | ||
| human_readable | No |
Changes observed during successful MCP inspections.
Input schema / examplesAdded value: +[
+ {
+ "expression": "*/5 * * * *"
+ }
+]Output schema / propertiesAdded value: +{
+ "expression": {},
+ "fields": {
+ "type": "object"
+ },
+ "human_readable": {
+ "type": "string"
+ }
+}Output schema / (root)Previous value: -nullNew value: +{
+ "additionalProperties": true,
+ "type": "object"
+}Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so safety needs no restating. The description adds genuine scope context beyond the annotations: 'standard 5-field cron (minute hour day month weekday)' tells the agent that 6-field/Quartz-style or seconds-prefixed expressions are out of scope and would likely fail.
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, zero padding, with the primary action stated first and the format constraint second. Every clause earns its place and nothing is buried.
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 single required parameter is fully covered. The only minor gap is error behavior for malformed or non-standard expressions and any timezone/Day-of-week numbering assumptions, which would help an agent predict failures.
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 'expression' parameter is documented with two examples in the schema itself, so the baseline is 3. The description's field-order parenthetical reinforces the format but adds little the schema and its examples do not already convey.
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 ('Parse a cron expression') and names the exact output ('human-readable schedule description'), so the input-to-output transformation is unambiguous. No sibling tool touches cron, so an agent can route to it without inspecting the schema.
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 name and one-line purpose – pass a cron string, get readable text – but the description never says when to reach for this instead of, say, timestamp_convert, nor does it flag any preconditions. For a self-evident pure utility this is adequate but unstated.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.