Compare conversation branch rules against its parent or main, writing differences to DIFF.md without modifying main.
生成分支 PROMPT 与父版本（或主线）的规则差异（写入分支 DIFF.md，不改主线）
| Name | Required | Description | Default |
|---|---|---|---|
| name | No | 实验分支名（只能用小写字母、数字、连字符；main 是保留名） | |
| root | Yes | Conversation Branch 工作区根目录 | |
| against | No | 改和指定分支比 | |
| against_main | No | 改和主线比，而不是和创建时的父版本比 |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already provide idempotentHint=true and destructiveHint=false, and the description adds the meaningful behavior that it writes into the branch's DIFF.md while leaving the mainline untouched. It could further state whether an existing DIFF.md is overwritten, but the side-effect boundary is clear.
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?
One compact sentence that front-loads the action and scope, then states the side effect and safety constraint. No filler or repetition of schema details.
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 tool with four parameters, high schema coverage, and annotations covering idempotence and non-destructiveness, the description supplies the key behavioral context: writing DIFF.md and not touching mainline. It lacks a note on return values, but with no output schema the write side effect is likely the primary result.
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%, so the schema carries parameter documentation. The description adds the 'parent version (or mainline)' distinction that maps to against/against_main, but it does not elaborate on name constraints or root semantics beyond what the schema already says.
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 states a specific verb and resource: generate rule differences between a branch PROMPT and its parent version or mainline, with an explicit side effect (write branch DIFF.md) and exclusion (don't modify mainline). This clearly distinguishes it from siblings like cb_compare and cb_status.
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 implies usage when a branch-diff artifact is needed and clarifies the main-vs-parent comparison options, but it doesn't explicitly say when to choose cb_diff over cb_compare or other siblings. No alternative tool or exclusion condition is named.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.