subscribe_addon

SERVEREchoRelay SOURCEhttps://mcp.echorelay.dev

Critical RISK CLASS

Category Financial

Parameters 11 required

Recommended Approval-gatedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/dev-echorelay-management/subscribe-addon.md

WHAT IT DOES

What subscribe_addon does on EchoRelay

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.

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.

RISK

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 definition Charges the saved payment method immediately, then auto-renews every 30 days until `unsubscribe_addon`

Risk signalsBulk/mass operation — affects multiple targets

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs subscribe_addon safely

PolicyLayer is an MCP gateway: it sits between your AI agents and EchoRelay, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For subscribe_addon, this is the rule to start with:

subscribe_addon Approval-gated

Any call to subscribe_addon is blocked until a human approves it. The rest of the server keeps working.

View as policy code

policy.json

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

GATE THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect EchoRelay, apply this rule, and every subscribe_addon call is checked against it from then on.

FAQ

Questions about subscribe_addon

What does the subscribe_addon tool do? +

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. It is categorised as a Financial tool in the EchoRelay MCP Server, which means it involves financial transactions. Block by default and require explicit approval.

What parameters does subscribe_addon accept? +

subscribe_addon accepts 1 parameter: addonKey. Required: addonKey. The full parameter table on this page comes from the server's own tool schema.

How do I enforce a policy on subscribe_addon? +

Register the EchoRelay MCP server in PolicyLayer and add a rule for subscribe_addon: 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 EchoRelay. Nothing to install.

What risk level is subscribe_addon? +

subscribe_addon is a Financial tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.

Can I rate-limit subscribe_addon? +

Yes. Add a rate_limit block to the subscribe_addon 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.

How do I block subscribe_addon completely? +

Set action: deny in the PolicyLayer policy for subscribe_addon. 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.

What MCP server provides subscribe_addon? +

subscribe_addon is provided by the EchoRelay MCP server (https://mcp.echorelay.dev). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

KEEP EXPLORING

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