Spawn a subtask from a running task, inheriting its deliverables and criteria, to explore alternative execution paths. Atomically marks the parent superseded without rewriting history.
Session 分叉：从 running 任务派生子任务（继承 deliverable/dependencies/acceptance_criteria），原子地把原任务标记 superseded→子任务 id。父任务不 rewrite history。用于探索不同执行路径/决策变更。返回新子任务 id。
| Name | Required | Description | Default |
|---|---|---|---|
| reason | Yes | 分叉原因（记到父 task） | |
| task_id | Yes | 要分叉的 running 父任务 id | |
| fork_title | 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 provided, the description carries full behavioral disclosure. It explicitly mentions the atomic supersede operation, that the parent does not rewrite history, and that it returns the new subtask id. It does not cover error cases or the subtask's initial state, but the core behavior is transparent.
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 a single, compact paragraph that front-loads the primary action (forking) and key effects. It is slightly verbose in Chinese but efficiently conveys essential information without unnecessary 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 forking operation with no output schema, the description covers the essential behavior, return value, and the parent's state change. It does not explain error conditions or the status of the created subtask, but given the tool's complexity and the presence of many related siblings, this is adequate.
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 67% (two of three parameters documented). The description adds minimal parameter-level meaning beyond the schema: it mentions inheritance of fields but does not elaborate on fork_title or the exact semantics of reason beyond what is already in the schema. With high coverage, baseline 3 is appropriate.
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 clearly states the tool spawns a subtask from a running task, inherits deliverables/dependencies/acceptance criteria, and atomically marks the parent as superseded. It is distinct from sibling tools like task_create (which creates independent tasks) and task_supersede (which only marks a task superseded without forking).
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 provides a clear use case: '用于探索不同执行路径/决策变更' (for exploring different execution paths or decision changes). It does not explicitly name alternatives or give when-not-to-use conditions, but the purpose is sufficiently clear for an agent to decide when to apply it.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.