Add a video to a playlist

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

Annotations already declare a non-read-only, non-idempotent, non-destructive, open-world mutation, so the safety profile is covered. The description adds the position semantics (0 = first), which is genuine behavioral context, but it does not state what happens on duplicate adds, whether the playlist must already exist, or the effect of create_if_missing.

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 with no filler, and the core action plus the identifying rule are front-loaded. The parenthetical is a compact and effective clarification.

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 mutation tool with no output schema, annotations covering the mutation profile, and partial schema coverage, the description is adequate but leaves out duplicate handling, existence requirements, and return information.

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 60%, so the schema documents playlist, channel, and create_if_missing itself. The description restates the playlist identifier forms and adds meaning for 'position' that the schema does not convey beyond minimum 0, which is useful; video_id remains undocumented in both places.

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?

States a specific verb and resource ('Add a video to a playlist') and clarifies the two accepted playlist identifiers. The verb cleanly separates it from remove_from_playlist and move_in_playlist, though it does not name those siblings 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?

Provides identification hints ('by playlist id or exact title') but no explicit when-to-use guidance against alternatives like create_playlist or move_in_playlist, and does not mention prerequisites such as channel selection or quota.

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