# get_audio_features_batch

Get audio features for MANY tracks in one call (up to 50 processed) — ideal for analysing a whole playlist at once. Identify each item by name (track/artist), by isrc (matched exactly first — best for CJK / K-pop / niche tracks whose fuzzy name-match misses), or both (ISRC first, name as the fallback). One bad entry never fails the batch. Items beyond the 50-per-call cap come back with found: false and backfill_status: "over_limit"; an item missing BOTH track and isrc comes back "invalid_no_query". Neither is processed or charged — the response's skipped field counts them, so split a long list into calls of <=50 and resubmit any skipped rows. Returns counts (found / not_found / skipped) plus a per-track results array, where each entry's result is the same feature object as get_audio_features (or null when not found), and isrc is echoed back. An item is billed only when it returns features or queues an on-demand ingest; an ISRC/name with no match anywhere is free. For a single track, use get_audio_features.

Agent View of the PolicyLayer registry record for `get_audio_features_batch`. HTML page: https://policylayer.com/tools/com-freqblog-music-metadata/get-audio-features-batch

## Facts

- Tool: `get_audio_features_batch`
- Server: FreqBlog Music Metadata (`https://mcp.freqblog.com/mcp`) — https://policylayer.com/tools/com-freqblog-music-metadata.md
- Homepage: https://github.com/https://mcp.freqblog.com/mcp
- Risk category: Read (Low risk)
- Registry record: grade D, identity unverified
- Server auth posture: open
- Server rate-limited: no
- Parameters: 1 (1 required)
- Recommended policy verdict: Allowed

## Parameters

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| `tracks` | array | yes | List of {track?, artist?, isrc?} objects. Up to 50 are processed per call; any extra (up to 200 accepted) come back skipped. Each item should carry `track` or ` |

Parameters from the server's own tool schema.

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "get_audio_features_batch",
    "arguments": {
      "tracks": []
    }
  }
}
```

## Why get_audio_features_batch is rated Low

This tool queries and retrieves metadata about music tracks without modifying, deleting, or executing operations. It processes up to 50 items in a single call and returns feature data. The response handling for invalid/over-limit entries confirms read-only behavior with no side effects. Batch retrieval does not elevate the severity beyond the baseline read operation.

From the tool's own definition: "Tool retrieves audio features (BPM, key, mood, genre) for tracks in batch; described as 'Get audio features for MANY tracks' with identification by name or ISRC. No modification, deletion, or execution capabilities mentioned."

## Use case

AI agents call get_audio_features_batch to retrieve information from FreqBlog Music Metadata without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

## Recommended policy (PolicyLayer)

Verdict: **Allowed**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches FreqBlog Music Metadata:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "get_audio_features_batch": {}
  }
}
```

## Other tools on FreqBlog Music Metadata (11)

- `build_setlist` — Read — https://policylayer.com/tools/com-freqblog-music-metadata/build-setlist.md
- `find_compatible_keys` — Read — https://policylayer.com/tools/com-freqblog-music-metadata/find-compatible-keys.md
- `find_tracks_by_bpm` — Read — https://policylayer.com/tools/com-freqblog-music-metadata/find-tracks-by-bpm.md
- `find_tracks_by_key` — Read — https://policylayer.com/tools/com-freqblog-music-metadata/find-tracks-by-key.md
- `get_audio_features` — Read — https://policylayer.com/tools/com-freqblog-music-metadata/get-audio-features.md
- `get_recommendations` — Read — https://policylayer.com/tools/com-freqblog-music-metadata/get-recommendations.md
- `get_related_artists` — Read — https://policylayer.com/tools/com-freqblog-music-metadata/get-related-artists.md
- `score_transition` — Read — https://policylayer.com/tools/com-freqblog-music-metadata/score-transition.md
- `search_catalog` — Read — https://policylayer.com/tools/com-freqblog-music-metadata/search-catalog.md
- `suggest_next_track` — Read — https://policylayer.com/tools/com-freqblog-music-metadata/suggest-next-track.md
- `tag_track` — Write — https://policylayer.com/tools/com-freqblog-music-metadata/tag-track.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

---

Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=com-freqblog-music-metadata · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/com-freqblog-music-metadata