tag_track
Get a compact, HONESTLY-LABELLED tag list for a track — energy / danceability / valence / acousticness / instrumentalness, plus a mood tag and a broad genre tag. It is a tag-shaped projection of the same open-data analysis get_audio_features returns (no audio upload, no extra compute), so it cost...
This record as markdown: /tools/com-freqblog-music-metadata/tag-track.md
What tag_track does on FreqBlog Music Metadata
AI agents use tag_track to create or update resources in FreqBlog Music Metadata, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your FreqBlog Music Metadata environment.
| Parameter | Type | Required | Description |
|---|---|---|---|
isrc | object | — | ISRC, e.g. 'USUM71900001'. |
mbid | object | — | MusicBrainz recording ID (UUID). Tags come from AcousticBrainz for that exact recording. |
track | object | — | Track title. Use with `artist` when known. Supply AT LEAST ONE of track/isrc/mbid/spotify_id/track_id. Sending several is fine — they resolve by precedence (tra |
artist | object | — | Artist name. Only used with `track`; improves accuracy. |
track_id | object | — | Catalog itunes_track_id from a search_catalog or get_audio_features result. |
spotify_id | object | — | Spotify track ID, 'spotify:track:...' URI, or open.spotify.com URL. Resolves ONLY tracks already mapped to a Spotify ID (<1% of the catalog) — prefer track (+ar |
Parameters from the server's own tool schema.
Why tag_track is rated Medium
An AI agent can call tag_track faster than any human can review: one bad instruction and it creates or modifies resources in FreqBlog Music Metadata by the hundred, each call as confident as the last.
Attacks that exploit this kind of access
The rule that runs tag_track safely
PolicyLayer is an MCP gateway: it sits between your AI agents and FreqBlog Music Metadata, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For tag_track, this is the rule to start with:
tag_track stays usable, but capped: an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect FreqBlog Music Metadata, apply this rule, and every tag_track call is checked against it from then on.
Questions about tag_track
Get a compact, HONESTLY-LABELLED tag list for a track — energy / danceability / valence / acousticness / instrumentalness, plus a mood tag and a broad genre tag. It is a tag-shaped projection of the same open-data analysis get_audio_features returns (no audio upload, no extra compute), so it costs the same 1 quota unit, charged only on a served result. The differentiator vs opaque taggers (e.g. Cyanite) is that EVERY tag carries its own confidence and provenance: - confidence: measured (our Essentia analysis) | derived (MIREX mood from valence+energy) | model-estimated (AcousticBrainz mood SVM probability — research-grade, raw prob in value) | catalog-genre (broad catalogue tag, not fine-grained). - provenance: essentia | valence+energy | acousticbrainz | catalog. value is the [0,1] score for numeric tags and null for label-only tags (mood category, genre). Provide AT LEAST ONE identifier: track (optionally with artist), isrc, mbid, spotify_id, or track_id (catalog itunes_track_id). If you know several, send them all — they resolve by precedence (track > isrc > track_id > mbid > spotify_id) and the rest are ignored, so you never have to pick. The broad, reliable coverage is the MEASURED tags from our Essentia analysis over the analysed catalogue (plus on-demand by name); MBID/ISRC additionally reach 7.5M+ AcousticBrainz recordings WHEN you supply that identifier. Returns { track, count, tags:[{tag, category, value, confidence, provenance}], disclaimer }. For the full numeric feature set use get_audio_features; for nearest tracks use a discovery tool. It is categorised as a Write tool in the FreqBlog Music Metadata MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
tag_track accepts 6 parameters: isrc, mbid, track, artist, track_id, spotify_id. The full parameter table on this page comes from the server's own tool schema.
Register the FreqBlog Music Metadata MCP server in PolicyLayer and add a rule for tag_track: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches FreqBlog Music Metadata. Nothing to install.
tag_track is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the tag_track rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for tag_track. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
tag_track is provided by the FreqBlog Music Metadata MCP server (https://mcp.freqblog.com/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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