diff --git a/apps/server/src/provider/Layers/ClaudeAdapter.test.ts b/apps/server/src/provider/Layers/ClaudeAdapter.test.ts
index e23148973e..7f89ad9ead 100644
--- a/apps/server/src/provider/Layers/ClaudeAdapter.test.ts
+++ b/apps/server/src/provider/Layers/ClaudeAdapter.test.ts
@@ -497,6 +497,74 @@ describe("ClaudeAdapterLive", () => {
     );
   });
 
+  it.effect("forwards mcpServers from providerOptions to query options", () => {
+    const harness = makeHarness();
+    return Effect.gen(function* () {
+      const adapter = yield* ClaudeAdapter;
+      const mcpServers = {
+        filesystem: {
+          command: "npx",
+          args: ["-y", "@modelcontextprotocol/server-filesystem", "/tmp"],
+        },
+      };
+      yield* adapter.startSession({
+        threadId: THREAD_ID,
+        provider: "claudeAgent",
+        runtimeMode: "full-access",
+        providerOptions: {
+          claudeAgent: { mcpServers },
+        },
+      });
+
+      const createInput = harness.getLastCreateQueryInput();
+      assert.deepStrictEqual(createInput?.options.mcpServers, mcpServers);
+    }).pipe(
+      Effect.provideService(Random.Random, makeDeterministicRandomService()),
+      Effect.provide(harness.layer),
+    );
+  });
+
+  it.effect("forwards plugins from providerOptions to query options", () => {
+    const harness = makeHarness();
+    return Effect.gen(function* () {
+      const adapter = yield* ClaudeAdapter;
+      const plugins = [{ type: "local" as const, path: "./my-plugin" }];
+      yield* adapter.startSession({
+        threadId: THREAD_ID,
+        provider: "claudeAgent",
+        runtimeMode: "full-access",
+        providerOptions: {
+          claudeAgent: { plugins },
+        },
+      });
+
+      const createInput = harness.getLastCreateQueryInput();
+      assert.deepStrictEqual(createInput?.options.plugins, plugins);
+    }).pipe(
+      Effect.provideService(Random.Random, makeDeterministicRandomService()),
+      Effect.provide(harness.layer),
+    );
+  });
+
+  it.effect("omits mcpServers and plugins when not provided", () => {
+    const harness = makeHarness();
+    return Effect.gen(function* () {
+      const adapter = yield* ClaudeAdapter;
+      yield* adapter.startSession({
+        threadId: THREAD_ID,
+        provider: "claudeAgent",
+        runtimeMode: "full-access",
+      });
+
+      const createInput = harness.getLastCreateQueryInput();
+      assert.equal(createInput?.options.mcpServers, undefined);
+      assert.equal(createInput?.options.plugins, undefined);
+    }).pipe(
+      Effect.provideService(Random.Random, makeDeterministicRandomService()),
+      Effect.provide(harness.layer),
+    );
+  });
+
   it.effect("treats ultrathink as a prompt keyword instead of a session effort", () => {
     const harness = makeHarness();
     return Effect.gen(function* () {
diff --git a/apps/server/src/provider/Layers/ClaudeAdapter.ts b/apps/server/src/provider/Layers/ClaudeAdapter.ts
index acbee86053..30b7c1e465 100644
--- a/apps/server/src/provider/Layers/ClaudeAdapter.ts
+++ b/apps/server/src/provider/Layers/ClaudeAdapter.ts
@@ -2585,6 +2585,12 @@ function makeClaudeAdapter(options?: ClaudeAdapterLiveOptions) {
           env: process.env,
           ...(input.cwd ? { additionalDirectories: [input.cwd] } : {}),
         };
+        if (providerOptions?.mcpServers) {
+          (queryOptions as Record<string, unknown>).mcpServers = providerOptions.mcpServers;
+        }
+        if (providerOptions?.plugins) {
+          (queryOptions as Record<string, unknown>).plugins = providerOptions.plugins;
+        }
 
         const queryRuntime = yield* Effect.try({
           try: () =>
diff --git a/packages/contracts/src/orchestration.ts b/packages/contracts/src/orchestration.ts
index 3208adc8bb..b31a2cc8fe 100644
--- a/packages/contracts/src/orchestration.ts
+++ b/packages/contracts/src/orchestration.ts
@@ -53,6 +53,8 @@ export const ClaudeProviderStartOptions = Schema.Struct({
   binaryPath: Schema.optional(TrimmedNonEmptyString),
   permissionMode: Schema.optional(TrimmedNonEmptyString),
   maxThinkingTokens: Schema.optional(NonNegativeInt),
+  mcpServers: Schema.optional(Schema.Record(Schema.String, Schema.Unknown)),
+  plugins: Schema.optional(Schema.Array(Schema.Unknown)),
 });
 
 export const ProviderStartOptions = Schema.Struct({