viewport_capture

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already flag readOnlyHint=false and destructiveHint=true; the description adds that the tool writes an image file and returns its path, which is core behavior. It does not explain the destructive implication, such as overwriting an existing file at the target path, but it does not contradict the annotations.

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 core action is front-loaded and clear: 'Grab the active viewport into an image file and return the path.' The purpose clause is helpful context, but the bilingual duplication (Chinese then English) makes the description roughly twice as long without adding unique information.

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 only one optional parameter and no output schema, the description covers the essential contract: what is captured, what is returned, and when it matters. The only notable omission is clarifying the destructiveHint/overwrite behavior, but overall the definition is sufficient for a low-complexity tool.

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?

The schema already documents the single optional 'path' parameter at 100% coverage, including the fallback to the render output folder with '.png'. The description only restates that a path is returned and adds no new parameter-level meaning, so the baseline score of 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 states a specific verb ('Grab'/'抓取'), a clear resource ('the active viewport'), and an explicit result ('into an image file and return the path'). The 'active viewport' qualifier helps distinguish it from viewport_capture_all and other viewport-management siblings.

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?

It provides a clear use case: 'this is how the AI gets to see what it just built,' implying the tool is for post-construction visual verification. However, it does not explicitly say when to use this instead of viewport_capture_all or other viewport tools, nor does it mention any exclusions.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.