MCP Client

Wayland Core is an MCP client. It connects to any Model Context Protocol server and registers that server’s tools alongside the built-in eight, so the model can call them the same way it calls Read or Bash. You declare servers in the config file.

Declare a server

Each server is a [mcp.servers.*] table. Pick a transport and supply the connection details:

# stdio: launch a local subprocess
[mcp.servers.filesystem]
transport = "stdio"
command = "npx"
args = ["-y", "@modelcontextprotocol/server-filesystem", "/Users/me/project"]

# stdio with an environment variable
[mcp.servers.github]
transport = "stdio"
command = "npx"
args = ["-y", "@modelcontextprotocol/server-github"]
env = { GITHUB_TOKEN = "ghp_xxx" }

# SSE: connect to a remote event-stream server
[mcp.servers.database]
transport = "sse"
url = "http://localhost:3001/sse"

# streamable HTTP: POST with optional headers
[mcp.servers.remote-tools]
transport = "streamable-http"
url = "https://tools.example.com/mcp"
headers = { Authorization = "Bearer xxx" }

Transports

Transport	How it connects	Use case
`stdio`	Launches a local subprocess, speaks over stdin and stdout.	Local servers run with `npx` or `uvx`.
`sse`	GET for the event stream, POST for requests.	Remote servers.
`streamable-http`	HTTP POST, with SSE for streaming responses.	Remote servers.

Deferral and eager loading

Config-file MCP servers are deferred by default: their schemas are not loaded into the system prompt at startup, only the tool names are registered, and the model loads a schema on demand with ToolSearch. This keeps the prompt small when a server exposes many tools.

To send a server’s full schemas from the first turn instead, set deferred = false:

[mcp.servers.small-toolset]
transport = "stdio"
command = "npx"
args = ["-y", "my-mcp-server"]
deferred = false

Naming

MCP tool names are used directly when there is no conflict. When a name collides with a built-in tool or another server’s tool, the engine auto-prefixes it as mcp__{server}__{tool}.

Startup flow

On launch the engine connects to every configured server, runs the MCP initialize handshake, calls tools/list to discover tools, registers them, and closes all connections cleanly on exit.