playlist_cover_from_track

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

With no annotations provided, the description carries the full burden and does well: it states the side effect (PUT /playlists/{id}/images), the image-selection algorithm (largest JPEG candidate ≤ 256 KB), and the quota impact (GET + PUT + one image fetch). It does not explicitly say it overwrites an existing cover, but the PUT verb strongly implies it.

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 sentences, dense with actionable information: the purpose, source-selection options, default behavior, endpoint, image constraint, and quota impact. No filler or repetition of schema details.

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 annotations and no output schema, the description covers the core behavior, endpoint, selection options, and quota. It is missing explicit return-value guidance and sibling routing, but the schema already documents the response_format parameter, so the agent can infer that output varies by that parameter.

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 100%, so the baseline is 3. The description adds useful semantics beyond the schema by explaining the default behavior (first track with art) and the image-fetch selection algorithm. It does not elaborate on dry_run or response_format, but those are already well described in the schema.

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 names a specific verb and resource: 'Set the playlist cover from a track album art,' followed by the concrete endpoint PUT /playlists/{id}/images. This distinguishes it from siblings like upload_playlist_cover (custom upload) and clone_playlist_cover (copy from another playlist).

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?

It clearly explains how to choose the source track: by position, by track URI, or defaulting to the first track with art. However, it does not explicitly state when to prefer this tool over siblings like upload_playlist_cover, nor does it mention any exclusions or alternatives, leaving the use case somewhat implied.

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