Stop a delegated Claude subagent task by its ID to prevent further file operations. Existing edits are kept, and any pending request may finish in the background.
Cancel a delegated task. Prevents subsequent file operations; an already pending proxy request may finish in the background. Existing edits are retained.
| Name | Required | Description | Default |
|---|---|---|---|
| agent_id | Yes | Agent ID returned by spawn or ask_claude. |
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 burden of behavioral disclosure. It meaningfully explains that only subsequent file operations are prevented, that an already pending proxy request may finish in the background, and that existing edits are retained. This gives an agent a realistic model of cancellation semantics rather than just 'cancel this thing'.
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?
The description is two tight sentences with no filler. It front-loads the core purpose, then adds only the behavioral details that materially affect an agent's expectations. Every clause 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 one-parameter mutating action with no output schema and no annotations, the description adequately explains what the tool does, what it prevents, and what it preserves. Minor gaps are the lack of error/status behavior and what happens to callers waiting on the canceled agent, but these are not essential for basic invocation.
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%, with agent_id already documented as 'Agent ID returned by spawn or ask_claude'. The tool description adds no parameter-level meaning, but the schema already provides sufficient guidance, 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?
The description opens with 'Cancel a delegated task', a specific verb plus resource that clearly identifies the operation. It is easily distinguished from siblings like spawn_claude_agent, list_claude_agents, and wait_claude_agents. The extra behavioral notes reinforce the purpose without obscuring it.
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?
The description states what the tool does but does not explicitly say when to use it over alternatives or when not to use it. An agent must infer from the verb 'cancel' that this is for terminating delegated tasks rather than creating, listing, or waiting on them. No exclusions or alternative routing are provided.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.