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

Annotations already establish readOnlyHint=true and non-destructive, but the description adds real behavioral context: the gating flag `video_live` that must be true for snapshot/OCR/control/commands/macros/agent operations, and the meaning of `can_control` as the user's drive-versus-watch permission. It does not mention pagination or result ordering, leaving a minor gap.

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?

Three sentences, purpose front-loaded in the first, followed by the identifier convention and the gating rules. Each sentence carries information, though the backtick-heavy second and third sentences are dense and could be split for readability.

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?

With no parameters, no output schema and a simple list operation, the description supplies the key returned field semantics and cross-tool prerequisites an agent needs. It omits return-shape details such as pagination or list length, a small gap given there is no output schema to fall back on.

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 baseline is 4. The description's discussion of `slot`, `video_live` and `can_control` describes returned fields rather than inputs, which is useful but not parameter semantics per se.

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 with scope ('List the farm phones the authenticated user can view'), and situates itself relative to the sibling phone tools by declaring it is the source of the `slot` UUID. An agent can distinguish this entry-point list tool from phone-snapshot-tool, phone-control-tool and the other phone siblings without opening schemas.

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?

Explicitly states when this tool is required ('Every other phone tool takes the `slot` UUID from here, never the human `name`') and the precondition for downstream tools to work (`video_live: true`). It also clarifies the condition under which the current user may act on a phone via `can_control`, giving concrete when/when-not guidance.

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