Screen MCP

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 effectively describes key behavioral traits: it's a one-shot operation (not session-based), mentions payload size considerations, and explains the response_mode options including environment variable fallback. However, it doesn't cover potential errors, performance characteristics, or system requirements.

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 efficiently structured with zero waste. It begins with the core purpose, provides usage guidelines, then details parameters in a clear format. Every sentence adds value: the first establishes the tool's nature, the second provides critical usage guidance, and the parameter explanations are essential given the lack of schema descriptions.

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 5-parameter tool with no annotations and no output schema, the description does an excellent job covering purpose, usage, and parameters. However, it doesn't describe the return value format (though response_mode hints at it) or potential error conditions. Given the complexity and lack of structured documentation elsewhere, it's very complete but missing some edge case information.

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?

With 0% schema description coverage, the description fully compensates by providing detailed semantic explanations for all 5 parameters. It explains what monitor_index values mean (0 for virtual desktop, 1..N for specific monitors), clarifies image_format options (png or jpeg), describes max_width behavior (resize while preserving aspect ratio), explains quality parameter applicability (JPEG only), and details response_mode options with their meanings and defaults.

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: 'Capture one screenshot in a single call.' It specifies the action (capture), resource (screenshot), and scope (one-shot). It distinguishes from siblings by explicitly mentioning the alternative session flow tools (start_screenshot_capture, get_screenshot_manifest, etc.).

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 explicit guidance on when to use this tool versus alternatives: 'Prefer this tool for small/medium payloads when a one-shot response is desired. For larger payloads or robust transport, use the session flow...' It names specific alternative tools and clearly defines the use case boundaries.

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