Create a new formatted draft post on Substack. Supports full markdown formatting. IMPORTANT: You MUST ALWAYS ask the user to confirm creation in a follow-up message BEFORE calling this tool with confirm_create=true. Never set confirm_create=true on the first request, even if the user explicitly a...
AI agents use create_formatted_post to create or update resources in Substack Mcp Plus — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Substack Mcp Plus environment.
This tool creates new draft posts, which is a Write operation (creates/modifies data reversibly). Severity is medium because: (1) it only creates drafts, not published content, limiting immediate impact; (2) drafts can be modified or deleted; (3) however, if an agent were to later publish these drafts without authorization, the blast radius increases.
From the tool's definition Tool description explicitly states 'Create a new formatted draft post on Substack' — a create operation that modifies data reversibly. The tool creates a draft, which can be edited or deleted, making it reversible and non-destructive.
Documented attack patterns abuse exactly the kind of access create_formatted_post gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Substack Mcp Plus, and nothing reaches the server without passing your rules. This is the rule we recommend for create_formatted_post:
{
"version": "1",
"default": "deny",
"tools": {
"create_formatted_post": {
"limits": [
{
"counter": "create_formatted_post_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}create_formatted_post 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.
Free to start. No card required.
Create a new formatted draft post on Substack. Supports full markdown formatting. IMPORTANT: You MUST ALWAYS ask the user to confirm creation in a follow-up message BEFORE calling this tool with confirm_create=true. Never set confirm_create=true on the first request, even if the user explicitly asks to create. This ensures users have time to review the content before creating. It is categorised as a Write tool in the Substack Mcp Plus MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Substack Mcp Plus MCP server in PolicyLayer and add a rule for create_formatted_post: 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 Substack Mcp Plus. Nothing to install.
create_formatted_post 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 create_formatted_post 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 create_formatted_post. 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.
create_formatted_post is provided by the Substack Mcp Plus MCP server (ty13r/substack-mcp-plus). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Substack Mcp Plus, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
12 Substack Mcp Plus tools catalogued and risk-classified — across an index of 43,000+ MCP servers.