youtube_add_videos

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

Annotations already declare this is a non-read-only, non-idempotent, open-world, non-destructive mutation, so the safety profile is covered. The description adds one genuinely non-annotated fact: the target playlist must be editable. It omits other relevant behavior such as the 50-video cap per call, duplicate handling, and quota/rate-limit implications.

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?

A single front-loaded sentence with no filler. It is efficient, though the brevity comes at the cost of the usage and batching details an agent would want.

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?

For a write tool that can add up to 50 items per call, the description says nothing about batch size, partial failure, or whether the operation is additive versus replacing. Annotations and a fully described schema offset some of this, but key operational context is missing.

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% and both parameters are documented in the schema, including that video_ids accepts watch/youtu.be/shorts URLs and that playlist_id accepts a URL with a list= parameter. The description adds nothing beyond that, so baseline 3 applies.

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?

"Add videos to an editable playlist" gives a specific verb (add) and resource (videos in a playlist), and the qualifier "editable" already rules out read-only/system playlists. It is clearly distinct from youtube_remove_videos, though it does not name or contrast with any sibling explicitly.

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?

There is no explicit when-to-use guidance, no mention of prerequisites such as authentication or ownership, and no routing to alternatives like youtube_clean_playlist_apply. The only implied constraint is the word "editable".

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