Cancel a pending scheduled send using its scheduleId. The email's content stays safe in your Drafts folder for later review or resending.
Cancel a pending scheduled send by scheduleId (from send_email with sendAt, or list_scheduled_emails). The draft stays in the Drafts folder, so the content is not lost.
| Name | Required | Description | Default |
|---|---|---|---|
| scheduleId | Yes |
| Name | Required | Description | Default |
|---|---|---|---|
| data | Yes |
Changes observed during successful MCP inspections.
v0.11.1Output schema / $schemaRemoved value: -"http://json-schema.org/draft-07/schema#"v0.11.0Output schema / (root)Previous value: -nullNew value: +{
+ "$schema": "http://json-schema.org/draft-07/schema#",
+ "additionalProperties": false,
+ "properties": {
+ "data": {
+ "additionalProperties": false,
+ "properties": {
+ "draftId": {
+ "type": "string"
+ },
+ "draftKept": {
+ "const": true,
+ "type": "boolean"
+ },
+ "scheduleId": {
+ "type": "string"
+ }
+ },
+ "required": [
+ "scheduleId",
+ "draftId",
+ "draftKept"
+ ],
+ "type": "object"
+ }
+ },
+ "required": [
+ "data"
+ ],
+ "type": "object"
+}v0.1.1Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are supplied, so the description carries the full burden, and it does disclose a genuinely non-obvious behavioral trait: cancellation does not destroy content because the draft remains in Drafts. It does not cover idempotency, whether a confirm/force flag exists, or what happens if the schedule already executed.
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 with zero filler; the action and its identifier are front-loaded, and the reassurance clause follows. Nothing redundant with the schema or title.
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?
An output schema exists, so return values need not be described, and the single parameter is explained. For a low-complexity mutation with no annotations, the description covers the main agent-facing risk (content loss) but leaves edge-case behavior (already-sent schedules, repeat calls) unstated.
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?
With a single parameter at 0% schema description coverage, the description must compensate, and it does: it explains that scheduleId identifies a pending scheduled send and traces its origin to send_email/sendAt or list_scheduled_emails. It adds no format or validation detail beyond that, but the origin explanation is the operationally important part.
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 ('cancel') and resource ('pending scheduled send'), scoped by scheduleId. It also names the sibling tools that produce the identifier (send_email with sendAt, list_scheduled_emails), so the agent can place it unambiguously against nearby tools like list_scheduled_emails.
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 parenthetical identifies exactly where a valid scheduleId comes from, which effectively tells the agent when this tool is applicable. It stops short of stating exclusions (e.g. what to do if the send already fired), so it is clear context rather than full when/when-not guidance.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.