Take screenshot

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

The description says it 'Saves PNG under an allowed path', implying a write side effect that modifies the filesystem, while the annotations declare readOnlyHint=true indicating no state change. This is a direct contradiction, so the description actually misleads the agent about the tool's side effects.

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 concise, front-loads the action and key details, and avoids fluff. However, it could be better structured to highlight the side-effect contradiction and missing parameter semantics.

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?

The tool is simple with 3 optional parameters, but the description omits the meaning of includeCursor, does not specify the default display when omitted, and fails to mention the return value (likely the saved file path). It also doesn't clarify behavior when an invalid path is given or permission is denied.

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 67%, so the baseline is 3. The tool description repeats the display ID and path behavior from the schema but adds no new details, especially for the includeCursor parameter which remains undocumented in both the schema and description.

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 captures the screen via screencapture and saves a PNG, distinguishing it from display-info tools like get_display_info in the sibling list. It specifies the verb and resource precisely with no ambiguity.

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 does not provide any guidance on when to use this tool versus alternatives, nor does it mention any exclusions or prerequisites beyond the permission requirement. It lacks explicit when-to-use or when-not-to-use context.

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