Cancel an in-progress sandbox run by killing and deleting its container; calling it on a finished run safely reports the final status instead of failing.
Cancel a run in progress, killing and deleting its container.
Safe to call on a run that has already finished; it reports the status it ended with instead of failing.
| Name | Required | Description | Default |
|---|---|---|---|
| run_id | Yes |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the safety profile itself and does so well: it discloses the destructive side effect (container killed and deleted) and the idempotent non-failure behavior on completed runs. It omits authorization requirements and whether the run's results/artifacts survive, which keeps it below 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?
Two short sentences with the destructive effect front-loaded and the edge-case behavior second. Nothing redundant, nothing padded.
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 single-parameter mutation with no output schema, the description covers purpose, side effects, and the repeat-call case, including what is returned when the run already finished. Only success-path return information and permission expectations are missing, which is acceptable for this complexity.
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 coverage is 0% and run_id has no description, but the single parameter is self-evident from the tool's purpose. The description adds nothing about identifier format or source, so it neither compensates nor misleads.
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 plus the concrete effect ('Cancel a run in progress, killing and deleting its container'). It is unmistakable against siblings start_run and get_result, since neither could be confused with cancellation.
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 an explicit safe-use condition: calling it on an already-finished run returns the final status rather than failing. It stops short of naming alternatives, but for a terminal cancel operation there is no real competing tool to route to.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.