ghost_update_newsletter

THE RISK

Medium Risk

Why ghost_update_newsletter needs a policy

This tool modifies existing data (newsletter configuration) in a reversible manner. While it can change important settings like sender information and display options that could affect how newsletters are distributed to subscribers, the changes are not destructive (the newsletter is not deleted) and not financial (no money moves).

From the tool's definition Tool description states it 'Updates an existing newsletter in Ghost CMS' with capabilities to modify 'name, description, sender settings, and display options.' The verb 'update' and the reversible nature of these modifications (name, description, settings)…

Documented attack patterns abuse exactly the kind of access ghost_update_newsletter gives an agent:

POLICY

How to control ghost_update_newsletter

PolicyLayer is an MCP gateway — it sits between your AI agents and Ghost MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for ghost_update_newsletter:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "ghost_update_newsletter": {
      "limits": [
        {
          "counter": "ghost_update_newsletter_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

ghost_update_newsletter 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.

Create a free account and register Ghost MCP Server — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

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EXPLORE

Related tools and policies

More Ghost MCP Server tools

Destructive ghost_delete_member Deletes a member from Ghost CMS by ID. This operation is permanent and cannot be undone. Destructive ghost_delete_newsletter Deletes a newsletter from Ghost CMS by ID. This operation is permanent and cannot be undon Destructive ghost_delete_page Deletes a page from Ghost CMS by ID. This operation is permanent and cannot be undone. Destructive ghost_delete_post Deletes a post from Ghost CMS by ID. This operation is permanent and cannot be undone. Destructive ghost_delete_tag Deletes a tag from Ghost CMS by ID. This operation is permanent and cannot be undone. Destructive ghost_delete_tier Deletes a tier (membership level) from Ghost CMS by ID. This operation is permanent and ca Execute ghost_batch_operations Execute multiple Ghost operations in a single request Execute ghost_cache_management Manage resource cache

All 39 Ghost MCP Server tools →

Write tools on other servers

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about ghost_update_newsletter

What does the ghost_update_newsletter tool do? +

Updates an existing newsletter in Ghost CMS. Can update name, description, sender settings, and display options. It is categorised as a Write tool in the Ghost MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on ghost_update_newsletter? +

Register the Ghost MCP Server MCP server in PolicyLayer and add a rule for ghost_update_newsletter: 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 Ghost MCP Server. Nothing to install.

What risk level is ghost_update_newsletter? +

ghost_update_newsletter is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit ghost_update_newsletter? +

Yes. Add a rate_limit block to the ghost_update_newsletter 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 ghost_update_newsletter completely? +

Set action: deny in the PolicyLayer policy for ghost_update_newsletter. 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 ghost_update_newsletter? +

ghost_update_newsletter is provided by the Ghost MCP Server MCP server (jgardner04/ghost-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Ghost MCP Server tool call.

Start from Ghost MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

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