musicbrainz-mcp-server

musicbrainz-mcp-server: get cover art

musicbrainz_get_cover_art

Read-onlyIdempotent

Cover Art Archive images for a release or release-group MBID: front/back flags, image types, full-resolution URLs, and 250/500/1200px thumbnail URLs. limit defaults to 25 and clamps above 100; offset defaults to 0. Pages retain archive order, totalCount counts all images, and hasArt describes the full archive even on an empty page. Follow the notice for the next offset. No art is a successful empty result; an unknown MBID fails with entity_not_found after a bounded MusicBrainz check. A release-group resolves to a representative release's art. URLs are linked, never rehosted; image copyright stays with rights holders.

Input Schema

Name	Required	Description	Default
`mbid`	Yes	Release or release-group MBID (hyphenated hexadecimal UUID; surrounding whitespace and uppercase accepted).
`limit`	No	Maximum images returned (default 25; values above 100 clamp to 100 with a notice).
`offset`	No	Zero-based image offset in archive order (default 0).
`entity_type`	No	Whether the MBID is a release (default) or a release-group.	release

Output Schema

Name	Required	Description
`cap`	No	Applied image limit when more remain.
`mbid`	No	The MBID that was queried.
`error`	No	Present when the call failed. Absent on success.
`shown`	No	Images returned when more remain.
`hasArt`	No	Whether any cover art exists for this entity.
`images`	No	Selected cover-art images in archive order (empty for no art or an exhausted page).
`notice`	No	Combined limit clamp, continuation, exhausted page, or no-art/existence-unconfirmed guidance.
`offset`	No	Effective zero-based image offset in archive order.
`truncated`	No	True when images remain after this nonempty page.
`entityType`	No	Whether the MBID was treated as a release or release-group.
`totalCount`	No	Exact image total before the limit and offset window.
`representativeRelease`	No	For a release-group query, the release MBID whose art was returned. Omitted for direct release queries.

Schema Changelog

Changes observed during successful MCP inspections.

Changed10 schema fields changedOct 23, 2026

addedInput schema / properties / limit

Added value: +{
+  "default": 25,
+  "description": "Maximum images returned (default 25; values above 100 clamp to 100 with a notice).",
+  "maximum": 9007199254740991,
+  "minimum": 1,
+  "type": "integer"
+}

addedInput schema / properties / offset

Added value: +{
+  "default": 0,
+  "description": "Zero-based image offset in archive order (default 0).",
+  "maximum": 9007199254740991,
+  "minimum": 0,
+  "type": "integer"
+}

changedOutput schema / anyOf

Previous value: -[
-  {
-    "not": {
-      "required": [
-        "error"
-      ]
-    },
-    "required": [
-      "mbid",
-      "entityType",
-      "images",
-      "hasArt"
-    ]
-  },
-  {
-    "required": [
-      "error"
-    ]
-  }
-]New value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "mbid",
+      "entityType",
+      "offset",
+      "images",
+      "hasArt",
+      "totalCount"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]

addedOutput schema / properties / cap

Added value: +{
+  "description": "Applied image limit when more remain.",
+  "type": "number"
+}

changedOutput schema / properties / images / description

Previous value: -"Cover-art images (empty when the entity has no art)."New value: +"Selected cover-art images in archive order (empty for no art or an exhausted page)."

changedOutput schema / properties / notice / description

Previous value: -"Present when the entity has no art: states that no images exist, or — when the MBID could not be checked against MusicBrainz — that its existence is unconfirmed."New value: +"Combined limit clamp, continuation, exhausted page, or no-art/existence-unconfirmed guidance."

addedOutput schema / properties / offset

Added value: +{
+  "description": "Effective zero-based image offset in archive order.",
+  "type": "number"
+}

addedOutput schema / properties / shown

Added value: +{
+  "description": "Images returned when more remain.",
+  "type": "number"
+}

addedOutput schema / properties / totalCount

Added value: +{
+  "description": "Exact image total before the limit and offset window.",
+  "type": "number"
+}

addedOutput schema / properties / truncated

Added value: +{
+  "description": "True when images remain after this nonempty page.",
+  "type": "boolean"
+}

Changed3 schema fields changedOct 13, 2026

changedInput schema / properties / mbid / description

Previous value: -"Release or release-group MBID (36-character UUID)."New value: +"Release or 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 — a value MusicBrainz rejects outright (HTTP 400). `entity_not_found`: The MBID is well-formed but no entity of the given entity_type exists with it (the archive returns 404 and the MusicBrainz check of the MBID returns 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 an upstream rejects it with HTTP 400. `entity_not_found`: The MBID is well-formed but no entity of the given entity_type exists with it (the archive returns 404 and the MusicBrainz check of the MBID returns 404). Other values are possible when a failure originates below the handler."

Changed3 schema fields changedSep 22, 2026

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 (the upstream returns HTTP 400). 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 — a value MusicBrainz rejects outright (HTTP 400). `entity_not_found`: The MBID is well-formed but no entity of the given entity_type exists with it (the archive returns 404 and the MusicBrainz check of the MBID returns 404). Other values are possible when a failure originates below the handler."

changedOutput schema / properties / error / properties / data / properties / reason / examples

Previous value: -[
-  "invalid_mbid"
-]New value: +[
+  "invalid_mbid",
+  "entity_not_found"
+]

changedOutput schema / properties / notice / description

Previous value: -"Notice when no art exists for the entity."New value: +"Present when the entity has no art: states that no images exist, or — when the MBID could not be checked against MusicBrainz — that its existence is unconfirmed."

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",
+      "entityType",
+      "images",
+      "hasArt"
+    ]
+  },
+  {
+    "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 (the upstream returns HTTP 400). Other values are possible when a failure originates below the handler.",
+          "examples": [
+            "invalid_mbid"
+          ],
+          "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",
-  "entityType",
-  "images",
-  "hasArt"
-]

First observedJun 16, 2026

TDQS

A4.1/5.0

Behavior5/5

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

Annotations only declare readOnly/openWorld/idempotent, yet the description adds substantial behavioral context: limit clamps above 100, archive order is preserved per page, totalCount and hasArt describe the full archive even on an empty page, unknown MBID fails only after a bounded MusicBrainz check, and URLs are linked rather than rehosted. This is exactly the extra context the lower annotation bar asks for.

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-loaded with what the tool returns, then paging semantics, then error behavior and licensing. Every sentence carries content, though the middle stretch is dense and slightly terse, which borders on overloading rather than waste.

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?

Given an output schema exists and annotations cover the safety profile, the description completes the picture with paging loop instructions, empty-vs-error distinction, release-group resolution, and licensing. An agent has everything needed to call it and to interpret the response 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 coverage is 100%, so baseline is 3; the schema already documents mbid, limit (including the clamp), offset, and entity_type. The description restates limit/offset defaults and adds the useful semantic that a release-group resolves to a representative release's art, but most parameter meaning is already carried by the schema.

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

Purpose4/5

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

The description uses a specific verb+resource ('Cover Art Archive images for a release or release-group MBID') and enumerates what it returns (front/back flags, image types, full-res and thumbnail URLs). It is clearly a distinct resource from the sibling get_release/get_release_group lookups, though it never names a sibling explicitly to route the agent.

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?

It supplies concrete operating context: paging via offset/limit with clamping, 'follow the notice for the next offset,' empty results are successful, unknown MBID yields entity_not_found, and release-group resolves to a representative release. It does not state when to prefer this over get_release or browse_entities, so there is no explicit exclusion guidance.

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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