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musicbrainz-mcp

by chrischall
OverviewSchemaSourceRelated ServersDiscussionsAdmin
TypeScript
Remote

Add or remove entities in a MusicBrainz collection

musicbrainz_modify_collection
Idempotent

Add or remove MusicBrainz entities (releases, artists, recordings, etc.) in your collections, with a confirmation step before changes take effect.

Instructions

Add or remove entities (releases, artists, recordings, release-groups, works, labels, places, areas, events) in one of YOUR MusicBrainz collections (needs OAuth: MUSICBRAINZ_OAUTH_* with the collection scope). Get the collection MBID from its URL (musicbrainz.org/collection/). Asks the user to confirm first: a confirmation prompt where the client supports one; otherwise the first call returns a preview and a confirmToken, and only a repeat call with that token proceeds (see MCP_CONFIRM_MODE). Nothing is changed before confirmation. Data from MusicBrainz (https://musicbrainz.org), the open music encyclopedia.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
mbidsYesMBIDs of the entities to add/remove
actionYesWhether to add to or remove from the collection
collectionYesMBID of the target collection
entityTypeYesPlural entity type the collection holds (e.g. "releases")
confirmTokenNoONLY for the two-step confirmation fallback (a client without MCP elicitation). The confirmToken from this same tool's phase-1 "confirmation-required" response, passed back ONLY after the user has seen that preview and explicitly approved it in chat — never on the first call, never invented, never reused. Call again with the same arguments. Ignored when the client supports elicitation.

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed2 schema fields changedv1.2.1
    • removedInput schema / properties / confirm
      Removed value: -{
-  "description": "Must be true to proceed. Without this, the tool returns a preview.",
-  "type": "boolean"
-}
    • addedInput schema / properties / confirmToken
      Added value: +{
+  "description": "ONLY for the two-step confirmation fallback (a client without MCP elicitation). The confirmToken from this same tool's phase-1 \"confirmation-required\" response, passed back ONLY after the user has seen that preview and explicitly approved it in chat — never on the first call, never invented, never reused. Call again with the same arguments. Ignored when the client supports elicitation.",
+  "type": "string"
+}
  2. Changed1 schema field changedv1.0.0
    • changedInput schema / $schema
      Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"
  3. First observedv0.2.2

TDQS

A4.3/5.0
Behavior5/5

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

Beyond the annotations, the description discloses crucial behavioral traits: a side-effect-free pre-confirmation phase, a preview + confirmToken fallback for clients without elicitation, that 'nothing is changed before confirmation', and the OAuth scope needed. This gives an agent a clear model of the mutation's safety and sequencing, well above what readOnlyHint/destructiveHint alone provide.

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

Conciseness4/5

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

The description is three dense sentences, with the core purpose front-loaded and supporting details (OAuth, confirmation, data source) following. Each sentence carries useful information, though the closing 'Data from MusicBrainz' attribution is not strictly needed for tool invocation, keeping it just short of a perfect 5.

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?

Given the tool's complexity (mutating action, OAuth, confirmation flow, multiple entity types) and the absence of an output schema, the description covers prerequisites, MBID sourcing, and the confirmation protocol thoroughly. It does not describe what a successful commit returns, but the confirmation flow and annotation hints (idempotent, non-destructive) make the behavior predictable enough for an agent to call it correctly.

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

Parameters3/5

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 tool description adds minimal parameter-specific meaning beyond what the schema already provides; the mention of deriving the collection MBID from a URL is helpful context, but the schema's per-parameter descriptions already explain action, entityType, mbids, collection, and confirmToken adequately. The description doesn't need to compensate for any coverage gap.

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?

The first clause 'Add or remove entities ... in one of YOUR MusicBrainz collections' pairs a specific verb (add/remove) with a precise resource (collection membership). It lists the entity types explicitly, and the resource is clearly distinct from the sibling tools (search, lookup, browse, submit_tags, submit_rating), so an agent can tell what it 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?

The description gives clear operational context: OAuth requirements (`MUSICBRAINZ_OAUTH_*` with `collection` scope), how to obtain the collection MBID from its URL, and the two-step confirmation flow. It does not explicitly name alternatives or state when not to use this tool, but the prerequisites and owned-collection framing make the intended usage obvious.

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

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