List videos

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

Annotations already establish readOnlyHint=true and openWorldHint=false, so the description correctly focuses on output behavior. It adds meaningful transparency by disclosing iframe and shadow DOM coverage, return fields, and platform detection, though it does not mention limitations such as dynamic content or ordering.

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 definition is a single front-loaded sentence that immediately states what is listed and then efficiently enumerates the useful return fields. There is no redundant phrasing or repetition of structured annotation data.

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 output schema, the description carries the return-value burden and does so by enumerating the key fields and coverage scope. It is nearly complete for a read-only listing tool, though it could clarify whether hidden media is included or how refs relate to video_control.

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%, and the single optional tabId parameter is already fully documented in the schema. The description does not add any further meaning about tabId, so the baseline score of 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 uses a specific verb, "Lists," and a precise resource, "every <video>/<audio> element on the page," including iframes and shadow DOM. It enumerates the returned fields and detected platforms, making it clearly distinguishable from siblings like video_control, video_frame, or video_captions.

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 usage by stating it lists all media elements on the page, but it gives no explicit guidance on when to choose this tool versus video_control, media_inspect, or page_snapshot. There are no exclusions or workflow suggestions such as using the returned refs before controlling playback.

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