MCP

@drover/mcp wraps @modelcontextprotocol/sdk with drover’s tool contract. Configure servers, build a runtime, drover prefixes every tool so cross-server collisions are impossible.

Config

import type { McpServerConfig } from "@drover/mcp";

const configs: McpServerConfig[] = [
  {
    id: "fixture",
    transport: "stdio",
    command: "bun",
    args: ["./mcp-servers/fixture/server.ts"],
  },
  {
    id: "linear",
    transport: "http",
    url: "https://mcp.linear.app",
    headers: { Authorization: `Bearer ${process.env.LINEAR_TOKEN}` },
  },
];

The discriminated union: stdio spawns a child process; http connects via streamable HTTP (also handles SSE).

Boot the runtime

import { createMcpRuntime } from "@drover/mcp";

const mcpRuntime = await createMcpRuntime(configs);
console.log(mcpRuntime.servers());
// [{ id: "fixture", transport: "stdio", toolCount: 2 }, ...]

Each server connects in parallel and lists its tools. Failed connects are isolated — one bad server doesn’t block the others, it just contributes 0 tools.

Declare in a spec

const spec = defineAgent({
  /* ... */
  mcpServers: ["fixture", "linear"],
});

spec.mcpServers is the allowlist for this agent — tools only show up from servers on the list.

Wire on the run

runAgent(spec, input, { mcpRuntime });

Tools come through prefixed: a server named fixture exposing a tool named compute shows up to the model as fixture__compute. Prefixing is opaque to the model — it sees the description and decides — but guarantees no collision when two servers both ship a query tool.

Tool schemas

MCP tools advertise JSON Schema. drover wraps via Type.Unsafe(jsonSchema) — the schema is preserved verbatim so the model sees the right arg shape; validation is the MCP server’s responsibility.

OAuth (planned)

For OAuth-protected servers, drover’s MCP runtime accepts headers up front but doesn’t yet auto-refresh expired tokens. Workaround: handle token refresh in your headers factory (re-create the runtime on expiry, or use a header-emitting closure once McpServerConfig accepts one).

Full OAuth refresh will migrate into @drover/mcp once the runtime layer gets HTTP control-plane support.

Lifetime

Connect once at app start, reuse across runs. Shutdown when the process exits:

process.on("SIGTERM", async () => {
  await mcpRuntime.close();
});

close() is best-effort — it tears down transports and clients but doesn’t fail if some are already gone.