cancel_scheduled_sendCalls a scheduled message back before it leaves. Nothing is sent and nothing is lost: it becomes an unsent draft again, with its recipients, text and files, whose draft_id the answer gives (delete_compose_draft throws it away). Refused once the message is already leaving.
| Name | Required | Description | Default |
|---|---|---|---|
| scheduled_send_id | Yes | The id of the scheduled message, as send_email, reply_to_conversation or list_scheduled_sends gives it. |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full behavioral burden. It clearly discloses side effects (nothing sent, message becomes an unsent draft with recipients/text/files), return information (draft_id), and the failure condition; missing permission/auth details keep it from a 5.
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?
Three compact sentences, front-loaded with the action and outcome. The parenthetical about delete_compose_draft is efficient and earns its place.
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 low-complexity one-parameter mutation with no output schema, the description covers the outcome, returned draft_id, failure mode, and alternative behavior. Nothing essential for correct invocation 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?
The sole parameter is fully documented in the schema at 100% coverage. The description does not add syntax or format meaning beyond the schema, so the baseline of 3 is appropriate.
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 action ('Calls a scheduled message back') and resource, with timing scope ('before it leaves') and an explicit contrast to delete_compose_draft. An agent can readily distinguish this from list_scheduled_sends or send_email.
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?
Gives a clear usage window and exclusion: use before the message leaves, and it is refused once already leaving. It names delete_compose_draft as an alternative for discarding, though it does not explicitly mention list_scheduled_sends for discovering IDs, which the schema covers.
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.