# find_compatible_keys

Given a Camelot key (e.g. "8A", "12B"), return the harmonically compatible keys for DJ mixing — the same key, the relative major/minor, and the adjacent +/-1 keys on the Camelot wheel. With extended=true also returns the +7/-7 energy-boost / energy-drop keys. Pure music theory — no catalog lookup and no quota cost. Pair with find_tracks_by_key to then pull actual tracks in each compatible key.

Agent View of the PolicyLayer registry record for `find_compatible_keys`. HTML page: https://policylayer.com/tools/com-freqblog-music-metadata/find-compatible-keys

## Facts

- Tool: `find_compatible_keys`
- 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: 2 (1 required)
- Recommended policy verdict: Allowed

## Parameters

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| `camelot` | string | yes | Camelot key, e.g. '8A' or '12B'. |
| `extended` | boolean | no | Also return the +7/-7 energy-boost / energy-drop keys. |

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": "find_compatible_keys",
    "arguments": {
      "camelot": "<camelot>"
    }
  }
}
```

## Why find_compatible_keys is rated Low

This is a straightforward data retrieval tool that performs music theory calculations and returns results. It does not create, modify, delete, execute code, or trigger external operations. The description explicitly states it is "pure music theory" with "no catalog lookup and no quota cost," confirming it is a read-only information lookup.

From the tool's own definition: "Tool returns harmonically compatible keys based on music theory ('Pure music theory — no catalog lookup'). It retrieves and returns data (compatible keys for a given Camelot key input) with no side effects, modifications, or external operations."

## Use case

AI agents call find_compatible_keys 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": {
    "find_compatible_keys": {}
  }
}
```

## Other tools on FreqBlog Music Metadata (11)

- `build_setlist` — Read — https://policylayer.com/tools/com-freqblog-music-metadata/build-setlist.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_audio_features_batch` — Read — https://policylayer.com/tools/com-freqblog-music-metadata/get-audio-features-batch.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