Cancel an active job and terminate its process tree to stop unwanted background execution.
Cancel an active job and terminate its process tree.
This tool declares no required parameters. Add optional parameters from the input schema as needed.
{
"id": 1,
"jsonrpc": "2.0",
"method": "tools/call",
"params": {
"arguments": {},
"name": "pi_cancel"
}
}| Name | Required | Description | Default |
|---|---|---|---|
| cwd | No | ||
| job_id | No |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden, and it does disclose the key behavioral trait that the whole process tree is terminated, signaling a destructive, likely irreversible operation. However, it says nothing about permissions, what happens to partial results or output already produced, or whether already-completed jobs are rejected.
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 wasted words, stating the action and its effect immediately. Its only weakness is that the terseness borders on under-specification rather than containing any verbose filler.
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, process-terminating mutation with no annotations, no output schema, and two undocumented parameters, the description is too thin. An agent lacks the information needed to know which parameter identifies the job or what the call returns.
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 0% and the description mentions neither parameter, so there is no explanation of how a job is identified via job_id or why cwd is needed. This is especially problematic because zero parameters are required, leaving the agent unable to tell which inputs are actually necessary to target a job.
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?
The description gives a specific verb and resource ('Cancel an active job') plus the concrete effect of terminating the process tree, which lets an agent distinguish it from siblings like pi_execute, pi_wait, and pi_result. It stops short of explicitly contrasting itself with those siblings, but the operation is unambiguous.
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 cancel versus when to wait (pi_wait) or fetch output (pi_result), and no prerequisites or preconditions are stated. The agent must infer the usage scenario entirely from the tool name.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.