# subscribe_addon

Subscribe the project owner to a monthly add-on (RPM upgrade, team seat, extended log retention, extra file storage in +5 GB blocks, …). Charges the saved payment method immediately, then auto-renews every 30 days until unsubscribe_addon — or until the subscription ends, after which the already-paid cycle stays active to its own end date and stops without further charges. Requires an active Pro/Scale subscription and a saved PM. RPM upgrades (rpm_*) are per-project and apply to THIS project automatically. Returns {addonKey, project, monthlyEurCents, transactionId, activatedAt, nextRenewalAt}. Owner-only; requires a token minted with the billing scope.

Agent View of the PolicyLayer registry record for `subscribe_addon`. HTML page: https://policylayer.com/tools/dev-echorelay-management/subscribe-addon

## Facts

- Tool: `subscribe_addon`
- Server: EchoRelay (`https://mcp.echorelay.dev`) — https://policylayer.com/tools/dev-echorelay-management.md
- Homepage: https://github.com/https://mcp.echorelay.dev
- Risk category: Financial (Critical risk)
- Registry record: grade F, identity unverified
- Server auth posture: open
- Server rate-limited: no
- Parameters: 1 (1 required)
- Recommended policy verdict: Approval-gated

## Parameters

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| `addonKey` | string | yes | Stable key from list_addons (e.g. "team_member", "rpm_2000", "log_retention", "file_storage"). |

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": "subscribe_addon",
    "arguments": {
      "addonKey": "<addonKey>"
    }
  }
}
```

## Why subscribe_addon is rated Critical

This tool directly initiates a financial transaction by charging the user's saved payment method immediately upon invocation and sets up recurring monthly charges. It fits squarely in the Financial category, which is the most severe. Misuse could result in unauthorized charges and ongoing financial obligations, warranting a critical severity rating.

From the tool's own definition: "Charges the saved payment method immediately, then auto-renews every 30 days until `unsubscribe_addon`"

Risk signals: Bulk/mass operation — affects multiple targets

## Use case

AI agents use subscribe_addon to commit financial operations through EchoRelay, usually the final step of a payment, billing, or trading workflow. A call moves real money.

## Recommended policy (PolicyLayer)

Verdict: **Approval-gated**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches EchoRelay:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "subscribe_addon": {
      "deny_if": [
        {
          "conditions": [],
          "on_deny": "Requires human approval."
        }
      ]
    }
  }
}
```

## Other tools on EchoRelay (77)

- `cancel_line_publish` — Destructive — https://policylayer.com/tools/dev-echorelay-management/cancel-line-publish.md
- `delete_credential` — Destructive — https://policylayer.com/tools/dev-echorelay-management/delete-credential.md
- `delete_endpoint` — Destructive — https://policylayer.com/tools/dev-echorelay-management/delete-endpoint.md
- `delete_line` — Destructive — https://policylayer.com/tools/dev-echorelay-management/delete-line.md
- `discard_dlq_entry` — Destructive — https://policylayer.com/tools/dev-echorelay-management/discard-dlq-entry.md
- `discard_draft_endpoint` — Destructive — https://policylayer.com/tools/dev-echorelay-management/discard-draft-endpoint.md
- `discard_line_draft` — Destructive — https://policylayer.com/tools/dev-echorelay-management/discard-line-draft.md
- `remove_member` — Destructive — https://policylayer.com/tools/dev-echorelay-management/remove-member.md
- `revoke_api_key` — Destructive — https://policylayer.com/tools/dev-echorelay-management/revoke-api-key.md
- `revoke_project_token` — Destructive — https://policylayer.com/tools/dev-echorelay-management/revoke-project-token.md
- `rollback_config` — Destructive — https://policylayer.com/tools/dev-echorelay-management/rollback-config.md
- `dry_run_endpoint` — Execute — https://policylayer.com/tools/dev-echorelay-management/dry-run-endpoint.md
- `duplicate_line` — Execute — https://policylayer.com/tools/dev-echorelay-management/duplicate-line.md
- `cancel_subscription` — Financial — https://policylayer.com/tools/dev-echorelay-management/cancel-subscription.md
- `change_plan` — Financial — https://policylayer.com/tools/dev-echorelay-management/change-plan.md
- `downgrade_addon` — Financial — https://policylayer.com/tools/dev-echorelay-management/downgrade-addon.md
- `retry_dlq_entry` — Financial — https://policylayer.com/tools/dev-echorelay-management/retry-dlq-entry.md
- `start_subscription` — Financial — https://policylayer.com/tools/dev-echorelay-management/start-subscription.md
- `start_topup` — Financial — https://policylayer.com/tools/dev-echorelay-management/start-topup.md
- `unsubscribe_addon` — Financial — https://policylayer.com/tools/dev-echorelay-management/unsubscribe-addon.md
- `default_endpoint_template` — Read — https://policylayer.com/tools/dev-echorelay-management/default-endpoint-template.md
- `get_billing` — Read — https://policylayer.com/tools/dev-echorelay-management/get-billing.md
- `get_config` — Read — https://policylayer.com/tools/dev-echorelay-management/get-config.md
- `get_dlq_entry` — Read — https://policylayer.com/tools/dev-echorelay-management/get-dlq-entry.md
- `get_endpoint` — Read — https://policylayer.com/tools/dev-echorelay-management/get-endpoint.md
- `get_key_policy` — Read — https://policylayer.com/tools/dev-echorelay-management/get-key-policy.md
- `get_line_draft` — Read — https://policylayer.com/tools/dev-echorelay-management/get-line-draft.md
- `get_metrics` — Read — https://policylayer.com/tools/dev-echorelay-management/get-metrics.md
- `get_project` — Read — https://policylayer.com/tools/dev-echorelay-management/get-project.md
- `get_receipts` — Read — https://policylayer.com/tools/dev-echorelay-management/get-receipts.md
- …and 47 more: https://policylayer.com/tools/dev-echorelay-management.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=dev-echorelay-management · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/dev-echorelay-management