add_tracks_to_playlist

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

Annotations already declare the write profile (readOnlyHint=false, idempotentHint=false, destructiveHint=false), so the description need not restate mutation semantics. It adds only the 'existing playlist' prerequisite; it does not explain duplicate-track behavior despite idempotentHint=false, any max-tracks limit, or ordering of appended tracks.

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?

One summary sentence plus a compact args block, front-loaded with the action and resource. No filler, though the args block is largely a restatement of parameter names.

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 two-parameter mutation tool with an output schema and safety annotations, the core call contract is covered. Missing behavioral details an agent may need before calling — duplicate handling given non-idempotent status, and any list-length limits — leave it short of 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?

Schema description coverage is 0%, so the description carries the parameter burden and largely does so: playlist_id is documented as accepting either an ID or a URI, and track_uris is documented as a list with a concrete URI format example. Minor gap: no statement on whether track order is preserved or whether duplicates within the list are allowed.

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 list of Spotify song URIs to an existing playlist'), and the 'song URIs' framing implicitly separates it from the movie-oriented sibling add_movie_songs_to_playlist. It never names a sibling explicitly, so sibling differentiation is only partial.

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?

'existing playlist' implies a precondition (the playlist must already exist), which hints at the boundary with create_playlist. Beyond that, there is no guidance on when to use this versus create_playlist, add_movie_songs_to_playlist, or dedupe_playlist.

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