Substack MCP Server

Substack CLI + 26-tool MCP server. Your IDE drafts replies via propose_reply. No API keys.

Local serverstdioPython

What is the Substack MCP server?

Substack CLI + 26-tool MCP server. Your IDE drafts replies via propose_reply. No API keys. Exposed over MCP by the substack mcp server, that capability becomes something an assistant can invoke while it works, not something you go and do afterwards.

What it actually does

Posts, notes, comments, replies, reactions, restacks, recommendations, search, profiles, feeds, automations, MCP server, Textual TUI. One Python install, one binary, MIT licensed.

Adding it to your client

The server ships on PyPI as substack-ops, so your MCP client can launch it on demand — there is no separate build step. Add the server block to your client's configuration, restart it, and the tools register themselves.

Its toolset

Everything the assistant can do here goes through one of these:

  • get_unanswered_comments — Returns the worklist: comments where you have not yet replied (any depth)
  • propose_reply — Dry-run only. Returns a token + payload preview. No write.
  • confirm_reply — Posts a previously-proposed reply by token. Idempotent via dedup DB. Token TTL 5 min

Configuration

You will need 2 environment variables: ANTHROPIC_API_KEY, OPENAI_API_KEY. The server will not start without them, which is usually why the tools fail to appear on a first run. Keep credentials in your client's env block or a secrets manager rather than in a file you might commit.

Caveats

  • It runs with your machine's permissions. That is convenient and also the reason to think about what you point it at before you approve a tool call.
  • Missing credentials fail quietly in some clients — if no tools show up, check the environment block first.
  • MCP clients confirm each tool call by default. Leave that on until you have watched what the substack mcp server does with a few real requests.

When to reach for it

This sits in the developer tooling group, where several servers overlap in what they claim to do but differ sharply once you actually set them up. Substack's toolset — get_unanswered_comments, propose_reply, confirm_reply — is a fair guide to whether it matches your workflow. It is maintained by 06ketan; worth a glance at recent repository activity before you build anything load-bearing on it.

We check each listing at SyncDev against the project's documentation before it goes live — if something here drifts out of date, it is a bug worth reporting.

Available tools

ToolWhat it does
get_unanswered_commentsReturns the worklist: comments where you have not yet replied (any depth).
propose_replyDry-run only. Returns a token + payload preview. **No write.**
confirm_replyPosts a previously-proposed reply by token. Idempotent via dedup DB. Token TTL 5 min.

How to install the Substack MCP server

{
  "mcpServers": {
    "substack-ops": {
      "command": "uvx",
      "args": ["substack-ops"],
      "env": {
        "ANTHROPIC_API_KEY": "your-value",
        "OPENAI_API_KEY": "your-value"
      }
    }
  }
}

Add to claude_desktop_config.json, then restart Claude Desktop.

Configuration

VariableDescriptionRequired
ANTHROPIC_API_KEYCredential the server authenticates with.Yes
OPENAI_API_KEYCredential the server authenticates with.Yes

Example prompts to try

  • Use Substack to get unanswered comments.
  • Use Substack to propose reply.
  • Use Substack to confirm reply.

Frequently asked questions

It connects Substack to MCP-compatible AI assistants such as Claude and Cursor, exposing 3 tools (get_unanswered_comments, propose_reply, confirm_reply) that the assistant can call on your behalf. Instead of copying data back and forth by hand, the assistant works with Substack directly.