diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6c2aa9c9..815b2ce6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- **Inline "Test" button per external MCP server.** Each server row in admin AI
+  settings now has its own "Test" button that runs an isolated connection check:
+  idle `Test` → green `OK · N` (with a tooltip listing the discovered tools, or
+  "No tools available") on success, or red `Failed` (tooltip with the sanitized
+  error) on a connection problem. State is per-row, so testing one server never
+  spins or recolours the others. (#170)
+
 - **Persistent AI-chat history as the source of truth + server-side export.**
   An assistant turn is now persisted to the database step by step: the row is
   inserted upfront as `streaming` and updated as each agent step finishes, then
diff --git a/apps/client/public/locales/ru-RU/translation.json b/apps/client/public/locales/ru-RU/translation.json
index e46a0579..41c7f6dc 100644
--- a/apps/client/public/locales/ru-RU/translation.json
+++ b/apps/client/public/locales/ru-RU/translation.json
@@ -1172,5 +1172,6 @@
   "OpenAI (official)": "OpenAI (официальный)",
   "Test": "Тест",
   "Failed": "Ошибка",
-  "OK · {{count}}": "OK · {{count}}"
+  "OK · {{count}}": "OK · {{count}}",
+  "No tools available": "Нет доступных инструментов"
 }
diff --git a/apps/client/src/features/workspace/components/settings/components/ai-mcp-server-row.test.tsx b/apps/client/src/features/workspace/components/settings/components/ai-mcp-server-row.test.tsx
index ecd5d2a6..5c6edd24 100644
--- a/apps/client/src/features/workspace/components/settings/components/ai-mcp-server-row.test.tsx
+++ b/apps/client/src/features/workspace/components/settings/components/ai-mcp-server-row.test.tsx
@@ -40,24 +40,37 @@ const baseServer = (over?: Partial<IAiMcpServer>): IAiMcpServer => ({
   ...over,
 });
 
+function tree(server: IAiMcpServer, testid: string) {
+  return (
+    <div data-testid={testid}>
+      <AiMcpServerRow
+        server={server}
+        onEdit={vi.fn()}
+        onDelete={vi.fn()}
+        onToggleEnabled={vi.fn()}
+      />
+    </div>
+  );
+}
+
 function renderRow(server: IAiMcpServer, testid: string) {
   const client = new QueryClient({
     defaultOptions: { mutations: { retry: false }, queries: { retry: false } },
   });
-  return render(
+  const utils = render(
     <QueryClientProvider client={client}>
-      <MantineProvider>
-        <div data-testid={testid}>
-          <AiMcpServerRow
-            server={server}
-            onEdit={vi.fn()}
-            onDelete={vi.fn()}
-            onToggleEnabled={vi.fn()}
-          />
-        </div>
-      </MantineProvider>
+      <MantineProvider>{tree(server, testid)}</MantineProvider>
     </QueryClientProvider>,
   );
+  // A rerender helper that swaps only the server prop (same QueryClient, so the
+  // row keeps its mutation state and the reset-on-change effect is exercised).
+  const rerenderWith = (next: IAiMcpServer) =>
+    utils.rerender(
+      <QueryClientProvider client={client}>
+        <MantineProvider>{tree(next, testid)}</MantineProvider>
+      </QueryClientProvider>,
+    );
+  return { ...utils, rerenderWith };
 }
 
 describe("AiMcpServerRow — inline Test button", () => {
@@ -95,6 +108,77 @@ describe("AiMcpServerRow — inline Test button", () => {
     );
   });
 
+  it("shows 'Failed' when the request itself rejects (401/403/500/network)", async () => {
+    // A real reject yields no { ok:false } payload — the row must read isError,
+    // not just mutation.data, or it would spin then silently revert to "Test".
+    testAiMcpServer.mockRejectedValue(new Error("Request failed"));
+    renderRow(baseServer(), "row");
+    const row = screen.getByTestId("row");
+
+    fireEvent.click(within(row).getByRole("button", { name: "Test" }));
+
+    await waitFor(() =>
+      expect(within(row).getByRole("button", { name: "Failed" })).toBeDefined(),
+    );
+  });
+
+  it("shows 'OK · 0' and a 'No tools available' tooltip for an empty tool list", async () => {
+    testAiMcpServer.mockResolvedValue({ ok: true, tools: [] });
+    renderRow(baseServer(), "row");
+    const row = screen.getByTestId("row");
+
+    fireEvent.click(within(row).getByRole("button", { name: "Test" }));
+
+    await waitFor(() =>
+      expect(within(row).getByRole("button", { name: /OK · 0/ })).toBeDefined(),
+    );
+  });
+
+  it("resets a stale result when url / transport / hasHeaders change", async () => {
+    testAiMcpServer.mockResolvedValue({ ok: true, tools: ["a", "b", "c"] });
+    const { rerenderWith } = renderRow(baseServer(), "row");
+    const row = () => screen.getByTestId("row");
+
+    fireEvent.click(within(row()).getByRole("button", { name: "Test" }));
+    await waitFor(() =>
+      expect(within(row()).getByRole("button", { name: /OK · 3/ })).toBeDefined(),
+    );
+
+    // Changing the URL must drop the stale green result back to idle "Test".
+    rerenderWith(baseServer({ url: "https://changed.example.com/mcp" }));
+    await waitFor(() =>
+      expect(within(row()).getByRole("button", { name: "Test" })).toBeDefined(),
+    );
+
+    // Same for the transport.
+    fireEvent.click(within(row()).getByRole("button", { name: "Test" }));
+    await waitFor(() =>
+      expect(within(row()).getByRole("button", { name: /OK · 3/ })).toBeDefined(),
+    );
+    rerenderWith(
+      baseServer({ url: "https://changed.example.com/mcp", transport: "sse" }),
+    );
+    await waitFor(() =>
+      expect(within(row()).getByRole("button", { name: "Test" })).toBeDefined(),
+    );
+
+    // And for the presence of auth headers.
+    fireEvent.click(within(row()).getByRole("button", { name: "Test" }));
+    await waitFor(() =>
+      expect(within(row()).getByRole("button", { name: /OK · 3/ })).toBeDefined(),
+    );
+    rerenderWith(
+      baseServer({
+        url: "https://changed.example.com/mcp",
+        transport: "sse",
+        hasHeaders: true,
+      }),
+    );
+    await waitFor(() =>
+      expect(within(row()).getByRole("button", { name: "Test" })).toBeDefined(),
+    );
+  });
+
   it("keeps each row's result isolated (testing one does not affect another)", async () => {
     // Resolve based on id so the two rows get different outcomes.
     testAiMcpServer.mockImplementation(async (id: string) =>
diff --git a/apps/client/src/features/workspace/components/settings/components/ai-mcp-server-row.tsx b/apps/client/src/features/workspace/components/settings/components/ai-mcp-server-row.tsx
index 04c305da..cb96fd42 100644
--- a/apps/client/src/features/workspace/components/settings/components/ai-mcp-server-row.tsx
+++ b/apps/client/src/features/workspace/components/settings/components/ai-mcp-server-row.tsx
@@ -35,7 +35,10 @@ export default function AiMcpServerRow({
 
   // The result colour/label reflects the connection params at the time of the
   // test. The row is keyed by id and never remounts, so a stale "OK"/"Failed"
-  // would otherwise stick after the URL/transport/auth changes. Reset on those.
+  // would otherwise stick after the connection params change. Reset on those.
+  // Note: `hasHeaders` is a presence flag only (header values are write-only and
+  // never returned), so this resets on adding/removing auth headers, NOT on
+  // rotating a token's value — that value-only change is invisible to the client.
   useEffect(() => {
     testMutation.reset();
     // eslint-disable-next-line react-hooks/exhaustive-deps
@@ -61,12 +64,25 @@ export default function AiMcpServerRow({
         ? result.tools.join(", ")
         : t("No tools available");
   } else if (result && "error" in result) {
+    // Server-reported failure ({ ok: false, error }, HTTP 200). The error string
+    // is already sanitized server-side (no secrets). The `"error" in result`
+    // guard is required: `result?.ok` optional-chaining doesn't narrow the union
+    // in the else branch, so a bare `else if (result)` fails to type-check.
     label = t("Failed");
     color = "red";
     variant = "light";
     icon = <IconX size={16} />;
-    // The error string is already sanitized server-side (no secrets).
     tooltip = result.error;
+  } else if (testMutation.isError) {
+    // The request itself rejected (401/403/500/network) — there is no result
+    // payload, so without this the row would silently revert to "Test".
+    label = t("Failed");
+    color = "red";
+    variant = "light";
+    icon = <IconX size={16} />;
+    tooltip =
+      testMutation.error?.["response"]?.data?.message ??
+      t("Failed to update data");
   }
 
   const testButton = (
@@ -78,9 +94,8 @@ export default function AiMcpServerRow({
       // (Test -> OK · 5 -> Failed).
       miw={88}
       leftSection={icon}
+      // Mantine disables the button automatically while loading.
       loading={testMutation.isPending}
-      // Only blocked while in flight — testing a disabled server is useful too.
-      disabled={testMutation.isPending}
       onClick={() => testMutation.mutate(server.id)}
     >
       {label}