piweb_fork_sessionDuplicate a session's current branch into a new independent session, leaving the original unchanged. Use it to start a separate line of work from any conversation point.
把会话当前分支整体复制成一个新会话（等价于侧边栏的 Fork）。原会话不受影响。用来「从这条线另开一条道」。
| Name | Required | Description | Default |
|---|---|---|---|
| name | No | 顺手给新会话起个名字 | |
| session | Yes | 会话 id / 名称 |
Changes observed during successful MCP inspections.
v1.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations declare readOnlyHint=false and openWorldHint=true but say nothing about what happens to the source; the description explicitly states 原会话不受影响 and that the branch is copied 整体, which clarifies the non-destructive fork semantics. It does not mention that repeated calls are non-idempotent (creating duplicate sessions), which is the one remaining behavioral 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?
Three short sentences, front-loading the core action and immediately following with the guarantee about the original session. The final sentence restates the use case already implied by the first, so it is mildly redundant but not wasteful.
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 two-parameter creation tool with no output schema, the description covers what is created and that the source is untouched, which is adequate to invoke it. It omits what the call returns (presumably the new session's identifier), which an agent would need to continue working with the fork.
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% for both parameters (session required, name optional), so the schema carries the parameter burden. The description adds no format, id-vs-name, or naming-collision guidance beyond what the schema already says, making the baseline 3 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 names a specific verb and resource: copying the session's current branch wholesale into a new session, and anchors it to a familiar UI concept (sidebar Fork). An agent can tell it produces a new session from an existing branch, though it never names the nearest sibling (piweb_create_session) it differs from.
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 phrase 「从这条线另开一条道」 implies the intended use case (branch off without disturbing the existing line), but there is no explicit when-to-use, when-not-to-use, or comparison against piweb_create_session. Usage is inferable rather than stated.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.