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: max duration enforcement, fixed capture rate, and output optimization for LLM temporal reasoning. However, it doesn't mention potential side effects like resource consumption or whether this is a read-only operation, leaving some gaps in behavioral transparency.

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 well-structured and appropriately sized. It starts with the core purpose, provides usage guidelines, lists behavioral constraints, and ends with output characteristics. Every sentence adds value with zero wasted words, making it highly efficient and front-loaded for quick understanding.

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 tool's complexity (5 parameters, no annotations, but has output schema), the description is reasonably complete. It covers purpose, usage context, key behavioral constraints, and output characteristics. The existence of an output schema means return values don't need explanation. However, the lack of parameter semantics and some behavioral details (like side effects) prevents a perfect score.

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 0%, so the description must compensate by explaining parameters. It mentions 'duration_seconds' indirectly through 'Max duration' and 'capture rate' through 'TIMELINE_FPS', but doesn't explain the semantics of monitor_index, image_format, max_width, or quality parameters. This leaves most parameters undocumented, failing to compensate for the low schema coverage.

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 a timeline in a single call' with a specific verb ('capture') and resource ('timeline'). It distinguishes from siblings by explicitly contrasting with the session flow tools (start_timeline_capture, get_timeline_manifest, etc.) for larger payloads, making the distinction clear and specific.

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 vs alternatives: 'Prefer this tool for short timelines when a one-shot JSON payload is acceptable. For larger timeline payloads or safer transport, use the session flow...' It names specific alternative tools and clearly defines the usage context, including exclusions for larger payloads.

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