fix(mcp-client): await Cordis startup discovery

packages/mcp/mcp-client/README.md

@@ -44,6 +44,7 @@ The model sees `mcp__github__create_issue`, `mcp__web__search`, … — the same
 | `url` | http | yes | MCP server URL |
 | `headers` | http | no | Extra headers (e.g. auth tokens) |
 | `toolCallTimeoutMs` | both | no | Timeout per `callTool` invocation (default 60000) |
+| `failOnStartupError` | both | no | Reject plugin activation when the initial connection or tool discovery fails (default `false`) |
 
 ## Tool naming
 
@@ -56,7 +57,7 @@ Every MCP tool has two names: the raw MCP name (sent on the wire in `tools/call`
 
 ## Behavior
 
-- On connect: plugin activation awaits `listTools()` and registers each tool via `ctx.tools.register()` under its public name before the composition starts its first turn. Initial connection failure is logged and activates with no tools.
+- On connect: plugin activation awaits `listTools()` and registers each tool via `ctx.tools.register()` under its public name before the composition starts its first turn. Initial connection or discovery failure is always logged; it rejects activation when `failOnStartupError` is true and otherwise activates with no tools.
 - Listens for `notifications/tools/list_changed` → re-syncs; a failed re-sync keeps the previous generation registered.
 - Tool execute: `client.callTool({ name: rawName, arguments }, { signal })` with timeout + abort support—the public name is never sent to the server.
 - Canonical success is `{ content: JsonValue[], structuredContent? }`; complete JSON MCP blocks survive for programmatic callers. A supported advertised `outputSchema` validates `structuredContent`; unsupported schema vocabulary falls back to unconstrained `JsonValue`.