MCP Server

MCP MCP server exists for a simple reason — assistants are far more useful when they can act on MCP directly instead of describing what you should do. TypeScript framework for building MCP servers with declarative definitions and observability.

What you get

@cyanheads/mcp-ts-core is the infrastructure layer for TypeScript MCP servers. Install it as a dependency — don't fork it. Your agent collaborates with you to design and build the tools, resources, and prompts for your server.

• Declarative definitions — — tool(), resource(), prompt() builders with Zod schemas; appTool()/appResource() add interactive HTML UIs
• Server-level orientation — — instructions on createApp/createWorkerHandler rides every initialize for the model. Cross-tool composition hints, regional notes, scope guidance — without leaking text into every tool description
• Server identity — — optional title, websiteUrl, description, icons (SEP-973) on createApp/createWorkerHandler flow to initialize serverInfo, the /.well-known/mcp.json server card, and the landing page
• Unified Context — — one ctx for logging, tenant-scoped storage, elicitation, cancellation, and task progress
• Auth — — auth: ['scope'] on definitions, checked before dispatch (no wrapper code). Modes: none, jwt, or oauth (local secret or JWKS)
• Task tools — — task: true for long-running ops; framework manages create/poll/progress/complete/cancel

What the assistant can call

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

• Builders — The Builders tool exposed by this server
• Context — The Context tool exposed by this server

Configuration and credentials

You will need 3 environment variables: MCP_HTTP_HOST, MCP_AUTH_SECRET_KEY, OPENROUTER_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.

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.

Choosing this one

Plenty of file and storage access 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. MCP's toolset — Builders, Context — is a fair guide to whether it matches your workflow. It is maintained by cyanheads; 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.
• 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 mcp mcp server does with a few real requests.