youtube_get_available_languages

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering the safety profile. The description adds the useful behavioral detail that the output distinguishes between manual and auto-generated subtitles, which is not captured by annotations. However, it does not disclose return format, pagination, or other potential behaviors, so the description adds only modest context.

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 short sentences: 'Available subtitle languages for a video. Shows manual vs auto-generated.' Both sentences carry meaningful information, and the key differentiator is front-loaded. No wasted words.

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 simplicity (single parameter), rich annotations, and no output schema, the description adequately conveys the core purpose and the manual/auto-generated distinction. However, it does not specify the exact return format (e.g., language codes, labels, structure), which would be helpful since no output schema exists. Still, for a simple read-only tool, it is largely complete.

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 schema covers 100% of parameters with the description 'YouTube video URL or ID', so the baseline is 3. The tool description provides no additional meaning about the 'url' parameter beyond what the schema already states, so no extra credit is warranted.

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 identifies the resource ('available subtitle languages for a video') and adds a distinguishing feature ('Shows manual vs auto-generated'), differentiating it from siblings like youtube_get_transcript and youtube_get_video_info. Though it lacks an explicit verb, the tool name and context make the retrieval purpose clear.

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 the tool is for checking which subtitle languages are available, but it does not explicitly state when to use this tool vs alternatives like youtube_get_transcript or youtube_get_video_info. No exclusions or alternative guidance is provided, so the usage context is implied rather than explicit.

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