Cancel a running standalone Temporal activity execution by specifying its activity ID, with optional run ID and namespace.
Cancel a running standalone activity execution
| Name | Required | Description | Default |
|---|---|---|---|
| run_id | No | Run ID for the standalone activity execution | |
| namespace | No | Temporal namespace for this operation; omit to use the server default | |
| activity_id | Yes | Standalone activity execution ID |
Changes observed during successful MCP inspections.
v1.10.1Input schema / properties / namespaceAdded value: +{
+ "description": "Temporal namespace for this operation; omit to use the server default",
+ "enum": [
+ "default"
+ ],
+ "minLength": 1,
+ "type": "string"
+}v1.9.0v1.5.0v1.3.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full behavioral burden and falls short. It does not say whether cancellation is graceful or immediate, whether it is reversible, what permissions are required, or what happens to an activity that has already completed. For a mutation tool with zero annotation coverage this is a meaningful gap.
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?
A single front-loaded sentence with no waste, though it is arguably too terse given the tool's mutation semantics and the crowded sibling set. Efficient but under-informative.
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 destructive-capable tool with no annotations, no output schema, and numerous similar siblings, the description leaves out safety profile, effect on completion, and sibling differentiation. It is not complete enough for an agent to invoke confidently.
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%, so run_id, namespace, and activity_id are already documented in the schema, and the description adds no syntax, format, or semantic detail beyond it. Baseline 3 applies when structured fields do the heavy lifting.
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 ('Cancel a running standalone activity execution'), which is clearer than a bare name restatement. However, it does not distinguish itself from close siblings like terminate_activity, batch_cancel_activities, or cancel_workflow, so an agent cannot tell why to prefer cancel over terminate without opening schemas.
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?
There is no guidance on when to use this tool versus the many available alternatives (terminate_activity, batch_cancel_activities, cancel_workflow). The word 'running' hints at a precondition but no explicit conditions, exclusions, or prerequisites are stated.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.