Excalibur MCP Server

Excalibur MCP server exists for a simple reason — assistants are far more useful when they can act on Excalibur directly instead of describing what you should do. FastMCP server for posting formatted content to X (Twitter) — Tollbooth-monetized, DPYC-native.

What you get

Sword-swift posting of pretty tweets to X (Twitter) via AI agents, monetized with Bitcoin Lightning micropayments through the DPYC(TM) Tollbooth protocol.

What the assistant can call

Once Excalibur is connected, these are the calls the assistant has available:

• Category — Tools
• Purchase — purchase_credits, check_payment
• Notarization — notarize_ledger, list_notarizations, get_notarization_proof
• Onboarding — get_operator_onboarding_status, get_patron_onboarding_status
• post_tweet — Post a text tweet with markdown-to-Unicode rich text formatting
• post_tweet_image — Post a tweet with a hero banner image (image URL or SVG rendered to PNG)
• get_x_profile — Fetch the connected X account's handle and name for this patron (free)
• create_post — Store a new post (draft or scheduled); returns its post_id
• get_post — Read one stored post by id (owner-scoped)
• list_posts — List your stored posts, server-side sorted, filtered, and paginated
• update_post — Patch a stored post (doc, publish_at, recurrence, status)
• delete_post — Delete a stored post (soft delete by default)

Setting it up

Setup follows the usual MCP pattern — install or clone the server, register it in your client's configuration file, restart the client.

Configuration and credentials

You will need 2 environment variables: NEON_DATABASE_URL, SCHEDULER_WORKER_URL. 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.

Choosing this one

Plenty of developer tooling servers cover similar ground. The differences that matter in practice are scope of access and how much setup stands between you and a working tool call. Excalibur's toolset — Category, Purchase, Notarization and 11 more — is a fair guide to whether it matches your workflow. It is maintained by lonniev; 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We check each listing at SyncDev against the project's documentation before it goes live — if something here drifts out of date, it is a bug worth reporting.

Before you rely on it

• 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.
• With 14 tools registered it takes up a noticeable share of the context window; turn it off in projects that never touch Excalibur.
• 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 excalibur mcp server does with a few real requests.