Client auto-resolves InputRequiredResult via existing callbacks (SEP-2322) (#2998)

examples/stories/mrtr/server.py

@@ -0,0 +1,39 @@
+"""Multi-round tool result (2026 era): a tool returns input_required and resumes from echoed state."""
+
+from mcp_types import ElicitRequest, ElicitRequestedSchema, ElicitRequestFormParams, ElicitResult, InputRequiredResult
+
+from mcp.server.mcpserver import Context, MCPServer
+from stories._hosting import run_server_from_args
+
+CONFIRM_SCHEMA: ElicitRequestedSchema = {
+    "type": "object",
+    "properties": {"confirm": {"type": "boolean", "description": "Proceed with the deployment?"}},
+    "required": ["confirm"],
+}
+
+
+def build_server() -> MCPServer:
+    mcp = MCPServer("mrtr-example")
+
+    @mcp.tool(description="Deploy to an environment, asking the user to confirm first.")
+    async def deploy(env: str, ctx: Context) -> str | InputRequiredResult:
+        responses = ctx.input_responses
+        if responses is None or "confirm" not in responses:
+            # First round: ask the client to elicit confirmation. request_state is opaque
+            # to the client; here it carries the step name so the retry can verify the echo.
+            ask = ElicitRequest(
+                params=ElicitRequestFormParams(message=f"Deploy to {env}?", requested_schema=CONFIRM_SCHEMA)
+            )
+            return InputRequiredResult(input_requests={"confirm": ask}, request_state="awaiting-confirm")
+        # Retry round: the client echoed request_state byte-exact and supplied the answer.
+        assert ctx.request_state == "awaiting-confirm", ctx.request_state
+        answer = responses["confirm"]
+        if isinstance(answer, ElicitResult) and answer.action == "accept" and (answer.content or {}).get("confirm"):
+            return f"deployed to {env}"
+        return f"deployment to {env} cancelled"
+
+    return mcp
+
+
+if __name__ == "__main__":
+    run_server_from_args(build_server)