Upload a custom cover image for a Spotify playlist as base64-encoded JPEG (max 256KB) to update its artwork.
Upload a custom cover image for a playlist (base64 encoded JPEG, max 256KB)
| Name | Required | Description | Default |
|---|---|---|---|
| playlistId | Yes | Spotify ID of the playlist | |
| imageBase64 | Yes | Base64 encoded JPEG image (max 256KB) |
Changes observed during successful MCP inspections.
v0.7.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden. The only behavioral detail it gives (base64 JPEG, max 256KB) merely restates the schema, and it omits key traits: that this overwrites any existing cover, what permission/scope is required, and how failures (oversize/invalid format) are reported.
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 the action first and the constraints parenthetically appended; no filler or redundancy.
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 tool with no output schema and no annotations, the description is adequate but shallow: it does not cover the destructive overwrite behavior, authentication requirements, or error conditions that an agent would need before calling a mutation.
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?
Both parameters are required and schema description coverage is 100%, so the schema already documents playlistId and imageBase64 fully. The description adds no format syntax, encoding caveats, or examples beyond what the schema states — baseline 3.
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 (Upload) plus resource (cover image for a playlist) and even the accepted format and size cap. It is trivially distinguishable from the sibling get-playlist-cover, which retrieves rather than sets the image.
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 intent is implied — call this when you want to set a playlist's cover art — but there is no explicit when/when-not guidance, no mention of the prerequisites (ownership, required auth scope), and no reference to the sibling get-playlist-cover for the read side.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.