AI agents use newsletters_add to create or update resources in Ghost MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Ghost MCP Server environment.
This tool creates new newsletters in Ghost CMS. While creation of newsletters is reversible (can be deleted via newsletters_delete), it constitutes a Write operation with medium severity—a compromised agent could create spam newsletters, send unwanted communications, or pollute the newsletter catalog.
From the tool's definition Tool name 'newsletters_add' indicates creation of a new newsletter. Server description mentions 'managing newsletters' and the sibling tools pattern (newsletters_browse, newsletters_delete) confirms newsletters as a primary resource.
Documented attack patterns abuse exactly the kind of access newsletters_add gives an agent:
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 newsletters_add:
{
"version": "1",
"default": "deny",
"tools": {
"newsletters_add": {
"limits": [
{
"counter": "newsletters_add_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}newsletters_add 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.
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newsletters_add. 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.
Register the Ghost MCP Server MCP server in PolicyLayer and add a rule for newsletters_add: 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.
newsletters_add is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the newsletters_add 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.
Set action: deny in the PolicyLayer policy for newsletters_add. 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.
newsletters_add is provided by the Ghost MCP Server MCP server (mfydev/ghost-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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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42 Ghost MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.