wechat_screenshot

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

Beyond the annotations (readOnlyHint, idempotentHint, destructiveHint), the description reveals that the tool auto-scrolls and stitches long screenshots by default, that output_path can be omitted to save to screenshots/, and that the response is a JSON object with success, data.path/width/height/segments, and message. These behavioral details help the agent anticipate side effects and response shape. No contradiction with 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?

Four short sentences, each adding new information: purpose, long-screenshot default, output_path default, return format. The most important action and defaults are front-loaded. No redundant or marketing language.

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 read-only screenshot tool with a rich schema and an output schema, the description covers the key defaults and return format. It does not mention prerequisites like the simulator being open or the meaning of 'segments', but these are minor given the existing schema and annotations. The description is sufficient for an agent to invoke the tool correctly in most cases.

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 context signal reports 0% schema description coverage, so the description must compensate, but it only details output_path's default location and implicitly full_page's default. Parameters like overlap, auto_port, page_path, and scroll_top are not explained in the description, requiring the agent to inspect the nested $defs. The $defs do contain descriptions, which mitigates this, but the description itself adds little parametric meaning beyond 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 opens with a specific verb and resource: '实时捕获当前小程序模拟器的界面截图' (capture the current mini-program simulator interface screenshot in real-time). It further clarifies the long-screenshot default and references the output path and return JSON, leaving no doubt about the tool's function. This clearly distinguishes it from sibling tools like wechat_build or wechat_navigate.

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 gives clear context that this is for capturing screenshots of the simulator and mentions default long-screenshot behavior. It does not, however, name any sibling tools or state when to prefer this over wechat_inspector or wechat_automator. A brief 'use this when you need a screenshot' would have been stronger, but the context is unambiguous enough.

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