musicbrainz-mcp-server

musicbrainz-mcp-server: get release group

musicbrainz_get_release_group

Read-onlyIdempotent

Release-group ("the album" above specific pressings) by MBID: primary type (Album/Single/EP) and secondary types (Live/Compilation), first-release date, artist credit, the list of releases (editions), tags/genres, and cover-art availability from the Cover Art Archive (image count and front/back flags for the release-group's representative release — the art musicbrainz_get_cover_art returns; use that tool for the image URLs). The embedded releases list is capped at one page (25); for the complete set of editions, call musicbrainz_browse_entities with target_type=release and link.release-group. For a specific edition's tracklist, take a release MBID from the releases list and call musicbrainz_get_release.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`mbid`	Yes	Release-group MBID (hyphenated hexadecimal UUID; surrounding whitespace and uppercase accepted).

Output Schema

TableJSON Schema

Name	Required	Description
`cap`	No	The one-page cap that was applied. Absent when not truncated.
`mbid`	No	Release-group MBID.
`tags`	No	Community tags/genres (may be empty).
`error`	No	Present when the call failed. Absent on success.
`shown`	No	Number of releases returned. Absent when not truncated.
`title`	No	Release-group title.
`notice`	No	Present when the releases list was capped (how to fetch the complete set of editions) and/or when cover-art availability could not be checked (why coverArt is omitted).
`coverArt`	No	Cover-art availability from the Cover Art Archive: the images of the release-group's representative release, the same art musicbrainz_get_cover_art returns (exists: false with count 0 when the archive has none). Omitted when the archive lookup could not complete — the notice says so.
`releases`	No	Releases (editions) in this group (one page; may be empty or capped — use browse for all).
`truncated`	No	True when the releases list hit the one-page cap and more editions exist. Absent when the full set fit in one page.
`primaryType`	No	Primary type (Album, Single, EP, Broadcast, Other). Omitted when absent.
`artistCredit`	No	Credited artists (may be empty).
`disambiguation`	No	Short qualifier. Omitted when absent.
`secondaryTypes`	No	Secondary types (Live, Compilation, Soundtrack, …). Omitted when none.
`firstReleaseDate`	No	Earliest release date across all editions. Omitted when absent.
`artistCreditString`	No	Display string of the artist credit with join phrases.

Schema Changelog

Changes observed during successful MCP inspections.

Changed3 schema fields changedOct 13, 2026

changedInput schema / properties / mbid / description

Previous value: -"Release-group MBID (36-character UUID)."New value: +"Release-group MBID (hyphenated hexadecimal UUID; surrounding whitespace and uppercase accepted)."

addedInput schema / properties / mbid / pattern

Added value: +"^\\s*[0-9A-Fa-f]{8}-[0-9A-Fa-f]{4}-[0-9A-Fa-f]{4}-[0-9A-Fa-f]{4}-[0-9A-Fa-f]{12}\\s*$"

changedOutput schema / properties / error / properties / data / properties / reason / description

Previous value: -"Machine-readable failure mode. Declared by this tool: `invalid_mbid`: The MBID is malformed or the all-zeros sentinel (MusicBrainz returns HTTP 400). `entity_not_found`: The MBID is well-formed but no release-group exists with it (MusicBrainz returns HTTP 404). Other values are possible when a failure originates below the handler."New value: +"Machine-readable failure mode. Declared by this tool: `invalid_mbid`: The MBID is malformed or the all-zeros sentinel (rejected before fetch), or MusicBrainz rejects it with HTTP 400. `entity_not_found`: The MBID is well-formed but no release-group exists with it (MusicBrainz returns HTTP 404). Other values are possible when a failure originates below the handler."

Changed3 schema fields changedSep 22, 2026

changedOutput schema / anyOf

Previous value: -[
-  {
-    "not": {
-      "required": [
-        "error"
-      ]
-    },
-    "required": [
-      "mbid",
-      "title",
-      "artistCredit",
-      "artistCreditString",
-      "releases",
-      "tags",
-      "coverArt"
-    ]
-  },
-  {
-    "required": [
-      "error"
-    ]
-  }
-]New value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "mbid",
+      "title",
+      "artistCredit",
+      "artistCreditString",
+      "releases",
+      "tags"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]

changedOutput schema / properties / coverArt / description

Previous value: -"Whether cover art exists (availability stub from WS/2)."New value: +"Cover-art availability from the Cover Art Archive: the images of the release-group's representative release, the same art musicbrainz_get_cover_art returns (exists: false with count 0 when the archive has none). Omitted when the archive lookup could not complete — the notice says so."

changedOutput schema / properties / notice / description

Previous value: -"How to fetch the complete list of editions when truncated."New value: +"Present when the releases list was capped (how to fetch the complete set of editions) and/or when cover-art availability could not be checked (why coverArt is omitted)."

Changed6 schema fields changedAug 21, 2026

changedInput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedInput schema / additionalProperties
```
Added value: +false
```

changedOutput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedOutput schema / anyOf

Added value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "mbid",
+      "title",
+      "artistCredit",
+      "artistCreditString",
+      "releases",
+      "tags",
+      "coverArt"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]

addedOutput schema / properties / error

Added value: +{
+  "additionalProperties": {},
+  "description": "Present when the call failed. Absent on success.",
+  "properties": {
+    "code": {
+      "description": "JSON-RPC error code for this failure.",
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    "data": {
+      "additionalProperties": {},
+      "properties": {
+        "reason": {
+          "description": "Machine-readable failure mode. Declared by this tool: `invalid_mbid`: The MBID is malformed or the all-zeros sentinel (MusicBrainz returns HTTP 400). `entity_not_found`: The MBID is well-formed but no release-group exists with it (MusicBrainz returns HTTP 404). Other values are possible when a failure originates below the handler.",
+          "examples": [
+            "invalid_mbid",
+            "entity_not_found"
+          ],
+          "type": "string"
+        },
+        "recovery": {
+          "additionalProperties": {},
+          "description": "Actionable next step for the caller.",
+          "properties": {
+            "hint": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "hint"
+          ],
+          "type": "object"
+        },
+        "retryable": {
+          "description": "Whether retrying may succeed.",
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable description of what went wrong.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "code",
+    "message"
+  ],
+  "type": "object"
+}

removedOutput schema / required

Removed value: -[
-  "mbid",
-  "title",
-  "artistCredit",
-  "artistCreditString",
-  "releases",
-  "tags",
-  "coverArt"
-]

Changed5 schema fields changedJun 20, 2026

addedOutput schema / properties / cap

Added value: +{
+  "description": "The one-page cap that was applied. Absent when not truncated.",
+  "type": "number"
+}

addedOutput schema / properties / notice

Added value: +{
+  "description": "How to fetch the complete list of editions when truncated.",
+  "type": "string"
+}

changedOutput schema / properties / releases / description

Previous value: -"Releases (editions) in this group (may be empty)."New value: +"Releases (editions) in this group (one page; may be empty or capped — use browse for all)."

addedOutput schema / properties / shown

Added value: +{
+  "description": "Number of releases returned. Absent when not truncated.",
+  "type": "number"
+}

addedOutput schema / properties / truncated

Added value: +{
+  "description": "True when the releases list hit the one-page cap and more editions exist. Absent when the full set fit in one page.",
+  "type": "boolean"
+}

First observedJun 16, 2026

TDQS

A4.4/5.0

Behavior4/5

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

Annotations already declare readOnly/idempotent/openWorld safety, so the description is not burdened with that. It adds genuinely useful behavioral detail: the embedded releases list is capped at one page (25), which warns the agent about truncation. It omits rate limits and auth, so not a full 5.

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?

Front-loads the tool's purpose and return contents before the routing sentences, and every sentence carries information. The opening sentence is dense with enumerated fields, which slightly hurts scannability but nothing is wasted.

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

Completeness5/5

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

An output schema exists so return values need not be documented, yet the description still summarizes payload contents and explicitly handles the truncation/routing gap. For a single-param lookup tool, nothing an agent needs to call it correctly is missing.

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?

Only one parameter and schema coverage is 100%, so the schema already documents the MBID format and whitespace tolerance. The description implies identification by MBID but adds no format or edge-case detail beyond the schema; baseline 3 applies.

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 ('Release-group ... by MBID') and immediately disambiguates the domain concept ('the album' above specific pressings). It also clearly sets itself apart from siblings get_release and browse_entities by scope.

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

Usage Guidelines5/5

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

Explicitly routes the agent: browse_entities with target_type=release and link.release-group for the full edition set, get_release for a specific edition's tracklist, and get_cover_art for image URLs. Both when-to-use and alternatives are named with concrete parameters.

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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