List published posts
AI agents call substack_get_posts to retrieve information from Substack MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves and enumerates existing published posts. It performs no creation, modification, deletion, or execution of external operations. The action is non-destructive and informational only. While the Substack server overall supports write and publish operations, this specific tool is purely for querying/retrieving data, making it a Read classification.
From the tool's definition Tool name and description: 'substack_get_posts: List published posts'. The verb 'list' combined with querying already-published posts indicates a read-only retrieval operation with no side effects.
Attacks that exploit this kind of access
List published posts. It is categorised as a Read tool in the Substack MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Substack MCP Server MCP server in PolicyLayer and add a rule for substack_get_posts: 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 Server. Nothing to install.
substack_get_posts is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the substack_get_posts 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 substack_get_posts. 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.
substack_get_posts is provided by the Substack MCP Server MCP server (jessicaruthabbott/my-substack-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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