play_youtube_video

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It states the tool plays videos but doesn't describe how (e.g., opens a new window, streams in background), error handling (e.g., invalid URLs), side effects (e.g., browser pop-ups), or performance (e.g., loading times). For a tool with potential user interaction and no annotation coverage, this is a significant 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?

The description is a single, efficient sentence with zero waste. It front-loads the core action ('Play YouTube video') and specifies the key detail ('in browser or VLC') without redundancy. Every word earns its place, making it highly concise and well-structured.

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 tool's moderate complexity (playback with platform choice), no annotations, and no output schema, the description is minimally adequate. It covers the basic purpose but lacks details on behavior, error cases, or integration context. With 100% schema coverage for inputs, it meets a baseline but doesn't fully compensate for missing behavioral transparency.

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 100%, with clear documentation for both parameters ('url' as YouTube video URL, 'player' with enum and default). The description adds no additional parameter semantics beyond what the schema provides, such as URL format examples or player-specific behaviors. Baseline 3 is appropriate when the schema does the heavy lifting.

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 action ('Play') and resource ('YouTube video'), specifying the target platforms ('in browser or VLC'). It distinguishes from siblings like 'get_video_info' or 'download_thumbnail' by focusing on playback rather than metadata extraction or content processing. However, it doesn't explicitly differentiate from all siblings (e.g., 'search_youtube' is for discovery, not playback).

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 guidance on when to use this tool versus alternatives. It doesn't mention prerequisites (e.g., needing a valid YouTube URL), exclusions (e.g., not for audio-only playback), or comparisons to siblings like 'get_video_info' for metadata. Usage is implied by the action but lacks explicit context.

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