video_capture_start

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

readOnlyHint=false already tells the agent this is not a passive read. The description adds meaningful context beyond that: the recording codec (ZMBV) and the captured surface (emulator screen). It omits the side effects an agent would want — output file location, whether an existing recording is overwritten, and whether a stop call is required.

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?

A single front-loaded sentence with no filler; the action, codec, and target are all stated immediately.

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 zero-parameter action the invocation bar is low, and the format/target detail is helpful. However, with no output schema and no description of the return value, the agent cannot tell whether this yields a file path, a status object, or nothing.

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 tool takes zero parameters, so the schema carries no semantics to document and the baseline of 4 applies. Nothing in the description is needed or missing on this dimension.

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 gives a specific verb+resource ("Start ZMBV video recording of the emulator screen"), making it immediately distinguishable from video_capture_stop and video_capture_status in the sibling list. It stops short of explicitly naming the counterpart tools, so it earns a 4 rather than a 5.

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?

Usage is implied by the name and description — start recording versus the sibling stop/status tools — but there is no explicit when-to-use guidance, no prerequisite (e.g. emulator must be running), and no statement of what happens if a recording is already in progress.

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