スクリーンショット

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

Annotations already declare readOnlyHint=true, and the description adds meaningful behavioral context: DRM-protected content (Netflix/Prime Video) appears black. It also discloses the image resolution and format, which is not present in the structured metadata.

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?

Three short sentences, front-loaded with the core action and output format, followed by use case and DRM caveat. Every sentence earns its place without repeating schema content.

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 simple read-only capture tool with one optional parameter, the description plus annotation is sufficient. It includes return format, intended usage, and a known limitation, so an agent has everything needed to call it correctly.

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%, and the optional device parameter is already well documented in the schema, so the description does not need to add parameter detail. Baseline 3 is appropriate because the description contributes no additional parameter semantics.

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 ('取得する') and resource ('TV画面のスクリーンショット') and even specifies the output format (960x540 JPEG). This makes the tool's function unmistakable and distinct from the sibling tools, none of which offer screen capture.

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?

Explicitly describes the intended use case: check the current display before operating on the TV. It does not name alternative tools or state exclusions, but the guidance is clear enough for an agent to know when to invoke this tool.

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