browser_video_chapter

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

The description claims 'Add a chapter marker' (a write/mutation operation), but the annotation readOnlyHint=true marks it as a read-only operation. This is a direct contradiction. The description also fails to disclose whether the marker is added to the recording file or just a UI overlay, and does not mention any 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?

Two short sentences, front-loaded with the action. No unnecessary words, but it could be slightly more structured by separating purpose from effect.

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 the contradiction and lack of usage guidance, the description is incomplete. It does not explain the effect of the duration parameter, the required nature of title, or how the chapter marker integrates with the video recording. The annotations contradict the description, reducing overall completeness.

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?

All three parameters are fully described in the input schema (100% coverage), so the description adds no extra meaning. 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 states a specific verb ('Add') and resource ('chapter marker to the video recording'), and distinguishes it from sibling video tools like browser_start_video and browser_video_show_actions. The visual effect ('full-screen chapter card with blurred backdrop') adds clarity.

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?

No guidance is provided on when to use this tool versus alternatives (e.g., during recording, prerequisites like an active recording session). There is no mention of exclusions or when not to use it.

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