Add tracks to playlist

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

With annotations limited to coarse hints, the description supplies valuable behavioral detail: read-modify-write behavior, duplicate skipping, and the merge-back write. This materially goes beyond what readOnlyHint/destructiveHint convey and is not contradicted by annotations.

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 tight sentences front-load the core action and add only one high-value behavioral detail after it. No filler or redundant restatement of the tool name.

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 four-parameter mutation with no output schema, the description covers the core behavior, ownership constraint, and deduplication semantics. It omits edge-case behavior such as error handling or non-existent playlists, but the schema and description together are sufficient for correct invocation.

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%, so the schema already documents all four parameters and their meanings. The description adds minimal parameter-level detail beyond echoing the append/prepend behavior, which is the appropriate baseline.

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 ('Append (or prepend)') and a specific resource ('tracks to a playlist owned by the logged-in user'), which distinguishes it from playlist metadata tools and track-removal siblings. It is immediately clear what action the tool performs.

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 gives clear context: use it to add tracks to a playlist the authenticated user owns, with optional prepend/append placement. It does not explicitly name alternatives such as update_playlist or remove_playlist_tracks, so it stops short of a 5.

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