MCP Screen Text

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It states what the tool does but lacks critical details: whether it requires permissions, how it handles multiple windows of the same application, what happens if the application isn't running, or the output format (e.g., file path, base64). This is inadequate for a tool that interacts with system applications.

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 a single, clear sentence with zero wasted words. It's front-loaded with the core purpose and appropriately sized for a simple tool, making it easy for an agent to parse quickly.

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?

Given the complexity of capturing application screens (system interaction, potential permissions) and the lack of annotations and output schema, the description is incomplete. It doesn't address behavioral aspects like error handling, output location, or dependencies, leaving significant gaps for an agent to use 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%, so the schema already fully documents both parameters (applicationName and format). The description adds no additional parameter semantics beyond what's in the schema, such as examples of valid application names or implications of format choice. Baseline 3 is appropriate when the schema does all the work.

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's purpose with a specific verb ('captures') and resource ('screenshot of a specific application window'), which distinguishes it from generic screen capture tools. However, it doesn't explicitly differentiate from sibling tools like 'capture_screen' or 'capture_screen_and_extract_text' beyond implying application-specific targeting.

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 no guidance on when to use this tool versus alternatives like 'capture_screen' (full screen) or 'capture_screen_and_extract_text' (which includes OCR). It mentions 'specific application window' but doesn't clarify prerequisites (e.g., application must be running) or exclusions.

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