Capture Screen

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

The description adds important behavioral context beyond the read-only annotation: it requires Screen Recording permission and falls back to the `screencapture` CLI if the native helper is unavailable. This discloses prerequisites and error-handling behavior, which is genuinely useful.

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 two sentences, front-loaded with the action, and every sentence adds value. It is concise and well-structured with no redundancy.

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 screenshot tool with thorough annotations and full parameter schema, the description covers the core behavior, permissions, and fallback. It does not state the return format, but given the lack of output schema and the tool's straightforward nature, this is a minor gap, not a critical omission.

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 input schema already provides 100% coverage with descriptions for both maxWidth and displayId. The description adds little beyond the schema, only reinforcing that main display is default. Since schema coverage is high, a baseline 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 clearly states the tool takes a screenshot of a full display, with a specific default (main display). The verb 'Take a screenshot' and resource 'full display' distinguish it from siblings like capture_region and capture_window.

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 provides clear context for when to use this tool: for full-display screenshots, with main display as default. It doesn't explicitly mention alternatives or exclusions, but the 'full display' wording implies usage scope and differentiates from region/window capture.

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