URL: /drover/reference/mcp

---
title: "@drover/mcp"
description: MCP runtime — stdio + http transports, tool prefixing, allowlist.
---

## `createMcpRuntime`

```ts
function createMcpRuntime(
  configs: readonly McpServerConfig[],
): Promise<McpRuntime>;
```

Connects every server in parallel, lists tools, wraps each as a
prefixed drover `ToolDef`. Failed connects don't block siblings —
they just contribute 0 tools.

## `McpServerConfig`

```ts
type McpServerConfig = McpStdioConfig | McpHttpConfig;

interface McpStdioConfig {
  id: string;
  transport: "stdio";
  command: string;
  args?: readonly string[];
  env?: Readonly<Record<string, string | null>>;
  cwd?: string;
}

interface McpHttpConfig {
  id: string;
  transport: "http";          // Streamable HTTP + SSE auto-negotiated
  url: string;
  headers?: Readonly<Record<string, string>>;
}
```

## `McpRuntime`

```ts
interface McpRuntime {
  tools(allowed?: readonly string[]): readonly AnyToolDef[];
  servers(): readonly McpServerInfo[];
  close(): Promise<void>;
}

interface McpServerInfo {
  id: string;
  transport: "stdio" | "http";
  toolCount: number;
}
```

`tools(allowed)` filters by server allowlist for harness composition.
`servers()` exposes connection state for diagnostics.

## `prefixedToolName` / `parsePrefixedToolName`

```ts
function prefixedToolName(serverId: string, toolName: string): string;
function parsePrefixedToolName(name: string): { serverId, toolName } | null;
```

Prefix format: `<server>__<tool>`. Tool names containing `__` are
split at the first occurrence; everything after stays in `toolName`.

## Tool schemas

MCP tool input schemas are preserved via `Type.Unsafe(jsonSchema)` so
the model sees the right arg shape. Validation is the MCP server's
responsibility — drover doesn't re-validate.