動画・画像を書き出す

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

With no annotations, the description carries the full burden. It usefully discloses the async flow (press, wait for download, save locally) and that it writes to a local path, but it omits critical behavioral details such as overwrite semantics for savePath, timeout/error handling, and what happens if the export button is unavailable.

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?

Two sentences, front-loaded with the action sequence and followed by the critical buttonName enumeration. There is no wasted phrasing, and the structure directly supports correct invocation.

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 UI-automation export tool with no annotations, no output schema, and only 50% schema description coverage, the description covers the core flow and the required buttonName values. However, it lacks essential context about failure modes, return behavior, and savePath overwrite semantics, so it is only minimally complete.

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 coverage is 50%: savePath has a schema description, but buttonName has none and no enum. The description compensates for buttonName by enumerating the three valid values ('MP4 を書き出す', '連番PNG（ZIP）', '透過PNG（ZIP・背景なし）'), which is a meaningful addition. It does not add constraints or format details for savePath 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 compound action: press the export button, wait for the download, and save it locally. It is clearly an export operation and distinguishes itself from primitive UI siblings like jizura_click by describing the full save workflow, though it does not explicitly contrast itself with those 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?

The description explains the mechanical steps but gives no guidance on when to use this tool versus alternatives, no prerequisites, and no exclusions. It does not state, for example, that it should be used instead of jizura_click when a download is expected.

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