start_overlay

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

Annotations indicate idempotentHint=true and destructiveHint=false, and the description does not contradict them. It adds useful detail about bottom_margin being relative to the TV video window height with a fallback to settings when the window is not found, but it does not explain overlay lifecycle or other side effects.

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 concise sentences with no filler. The primary purpose is stated first, and the most ambiguous parameter is clarified immediately after.

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 7 parameters, no schema descriptions, no output schema, and a large sibling set, the description is incomplete. It addresses only one parameter's semantics and offers no guidance on overlay behavior, return values, or when to invoke it over related tools.

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 for the 7 parameters. Only bottom_margin receives any semantic explanation; color, store_id, subtitle, font_size, font_family, and outline_width are left to inference from their names.

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 starts a tvsub NSPanel overlay with a selected subtitle and style, using a specific verb and resource. It is distinguishable from stop_overlay by its action, but it does not explicitly differentiate itself from related tools like load_subtitle or set_style.

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 no explicit guidance on when to use start_overlay versus alternatives such as load_subtitle, set_style, or stop_overlay. It implies its use by naming what it does, but it does not state conditions, prerequisites, or exclusions.

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