voodoosms_cancel_scheduled_messageWRITE: cancels one SMS that was scheduled through the send API, so it will not be sent. A message that has already gone out cannot be cancelled. Whether credits are refunded for a cancelled message is not documented by the vendor. Voodoo SMS REST: DELETE /schedule/{id}.
| Name | Required | Description | Default |
|---|---|---|---|
| id | Yes | The scheduled message id (id from list_scheduled_messages). |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations only carry destructiveHint=true, so the description adds real value: it says what is destroyed (the pending send), states the irreversibility boundary for already-sent messages, and honestly flags that credit refund behavior is undocumented rather than guessing. It omits auth requirements and error behavior for an invalid id.
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?
Four short sentences, front-loaded with the write nature and effect; each sentence carries distinct information (action, limitation, refund caveat, endpoint) with no repetition.
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 one-parameter mutation with no output schema, the description covers effect, constraint, and undocumented side effect (refunds), which is sufficient to call it correctly. Only error/idempotency behavior is left 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?
Schema description coverage is 100%, and the schema already documents that the id comes from list_scheduled_messages. The description adds no syntax, format, or edge-case detail beyond that, so the baseline of 3 applies.
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?
Names a specific verb (cancels) and resource (one SMS scheduled through the send API) and states the effect (it will not be sent). It is clearly distinguishable from siblings like list_scheduled_messages and send_sms without opening any 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?
Explicitly states the precondition and the exclusion: the message must have been scheduled, and one that has already gone out cannot be cancelled. It does not name a specific alternative tool for the already-sent case, but the when/when-not boundary is clear.
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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