@jam-jam/convert-mcp

Rename, re-cover or reorder a playlist

jj_update_playlist

Edits a playlist's name, cover emoji, or ordered song list, replacing the song list only when supplied so untouched fields stay the same.

Instructions

Changes one or more fields of a playlist: name, coverEmoji (null removes it), and songIds, which REPLACES the whole content and its order. Only the fields you pass move. To reorder, read the playlist with jj_get_playlist first and send the full list back in the new order.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "playlistId": "<playlistId>"
    },
    "name": "jj_update_playlist"
  }
}

Input Schema

Name	Required	Description
`name`	No	New name.
`ifMatch`	No	The `updatedAt` you last read for this object. When set, the write is refused with a conflict error if anything changed it since (another device, or the Jam Jam app). Without it, last writer wins. Use it whenever you read, decided, then write.
`songIds`	No	Ordered content of the playlist; the order is what the user will see and is never re-sorted. Every id must be a live song of this account, otherwise the whole call fails: a half-created playlist would be worse than a refusal.
`coverEmoji`	No	New cover emoji; null removes it.
`playlistId`	Yes	Stable playlist id ("pl_...").

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.3.2Nov 13, 2026

TDQS

A4.4/5.0

Behavior4/5

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

No annotations are supplied, so the description carries the full behavioral burden, and it discloses the most important trait: songIds REPLACES the entire content and order rather than merging, and coverEmoji=null removes the cover. It omits permission/auth requirements and what is returned, but the atomic-failure condition for invalid song ids is covered by the schema.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Three tight sentences with zero filler, front-loading the destructive replacement semantics before the reorder workflow. Capitalized REPLACES correctly draws attention to the highest-risk behavior.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a 5-parameter mutation with no annotations and no output schema, the description covers the fields, the partial-update model, the destructive songIds semantics, and the reorder workflow. It could say more about what happens on an unknown playlistId or what the call returns, but those are modest gaps given the rich schema.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the baseline is 3; the description still adds meaning by framing songIds as a destructive full replacement whose order is user-visible, and by clarifying that passing null removes the cover. It does not explain ifMatch semantics, but the schema already does that thoroughly.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('Changes one or more fields of a playlist') and enumerates the exact mutable fields: name, coverEmoji, songIds. The REPLACES-whole-content emphasis on songIds distinguishes this from an additive or reorder-only tool, so an agent can tell what this does without opening the schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives explicit procedural guidance for the non-obvious case: 'To reorder, read the playlist with jj_get_playlist first and send the full list back in the new order,' naming the sibling to use. It also clarifies the partial-update contract ('Only the fields you pass move'). There is no explicit when-not-to-use or guidance on preferring jj_update_song/jj_create_playlist, keeping it 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.