start_session

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

The description discloses that the session makes subsequent operations faster and requires scrcpy-server, but does not specify behavior on session duplication, resource locking, or error states. Since no annotations are provided, the description carries the full burden and offers moderate 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 two sentences, front-loaded with purpose and benefit, and includes a prerequisite. Every sentence adds value, with no wasted words.

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 tool with three optional parameters and no output schema, the description adequately covers purpose, benefit, and prerequisite. However, it omits details on return values or success/failure indicators, which would improve completeness.

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 description does not add any parameter-specific information beyond the input schema, which already fully covers the three parameters (serial, maxSize, maxFps). Given high schema coverage, baseline 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's purpose: starting a scrcpy session for fast input control and screenshots. It differentiates from siblings like stop_session and implies its role in enabling faster operations for tools like tap and swipe.

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 implies when to use the tool (before tap/swipe/text/screenshot to gain speed benefits) and mentions a prerequisite (scrcpy-server installation), but does not explicitly state when not to use it or provide alternatives.

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