Start async display recording

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

Annotations cover safety (non-readOnly, non-destructive, non-idempotent, openWorld), so the bar is lower. The description still adds real operational context beyond annotations: capture is non-blocking and only one active session per (serial, displayId) is allowed. It omits what a session produces and how it is terminated.

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?

Two tight sentences, zero filler, with the non-blocking behavior front-loaded and the concurrency constraint as the closing caveat. Every clause carries information.

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?

An output schema exists so return values need not be explained, and annotations carry the safety profile. The description supplies the key behavioral traits (async, single-session-per-target), but does not mention lifecycle pairing with mobile_record_stop or mobile_record_mark, a minor gap for a session-starting tool.

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 coverage is 100%, so both serial and displayId semantics (exact ADB serial, framework logical display ID vs SurfaceFlinger ID) are already fully documented in the schema. The description adds no parameter-level detail, making the baseline 3 correct.

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?

States a specific verb and resource: 'Start a non-blocking screenrecord on one logical display.' The 'non-blocking' qualifier and 'one logical display' scope meaningfully distinguish it from a generic record sibling, but no sibling (e.g. mobile_screen_record, mobile_record_stop) is named for explicit contrast.

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?

'so input tools can run during capture' tells the agent the condition that selects this tool over a blocking capture. No exclusion or explicit pointer to mobile_screen_record / mobile_record_stop, so it stops short of full alternative routing.

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