Retrieves the current unit of measurement for the EDA frontend, compatible with schematic and PCB canvases, to identify the active unit for design operations.
sys_Unit.getFrontendDataUnit() -> Promise<ESYS_Unit | undefined> 获取 EDA 前端数据单位跨度 remarks: 此处指的是前端用户可以切换的单位，需要同时兼容原理图和 PCB 画布 returns: 单位
| Name | Required | Description | Default |
|---|---|---|---|
| args | No | 按官方签名顺序排列的JSON参数数组 | |
| windowId | No | 目标EDA窗口ID；省略时使用当前活动窗口 |
Changes observed during successful MCP inspections.
v2.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description must fully disclose behavior. It states the return type (Promise<ESYS_Unit | undefined>) and cross-canvas compatibility, but does not mention that this is a read-only operation, any side effects, prerequisites (e.g., whether a windowId is needed), or error conditions. Significant behavioral gaps remain.
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 concise, with signature, purpose, remarks, and returns in a compact layout. It is front-loaded with the signature and includes the key compatibility context. Could be slightly cleaner (mixed language, redundant 'returns' line), but overall efficient.
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?
No output schema exists, so the description should clarify the return structure. It only says 'returns: 单位' without detailing the ESYS_Unit type or the possible undefined case. It also doesn't explain how windowId affects the result or mention exceptions. For a simple getter, this is moderate but incomplete.
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% (both `args` and `windowId` have descriptions), so the baseline is 3. The tool description adds no further meaning about parameters; it only repeats the generic 'official signature order' for args and the windowId usage already captured in the schema.
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 identifies the verb ('获取' - get) and resource ('前端数据单位' - frontend data unit), and the remark clarifies it refers to the user-switchable unit used across both schematic and PCB canvases. This distinguishes it from the sibling unit conversion tools, though the term '跨度' (span) is slightly ambiguous.
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 remark '需要同时兼容原理图和 PCB 画布' implies this tool is the general getter for the current unit in any canvas, providing some context. However, it lacks explicit guidance on when to use this tool versus the conversion tools (e.g., eda_sys_unit_inch_to_mm), and no when-not or alternatives are mentioned.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.