diff --git a/src/adapters/ollama-native.ts b/src/adapters/ollama-native.ts
index 726fe55ad49..2f95c5dbdc9 100644
--- a/src/adapters/ollama-native.ts
+++ b/src/adapters/ollama-native.ts
@@ -88,6 +88,7 @@ interface NativeStreamToolCall {
   nativeIndex?: number;
   arguments: Record<string, unknown>;
   argumentBytes: number;
+  metadataBytes: number;
 }
 
 interface NativeStreamState {
@@ -106,6 +107,10 @@ type NativeReadResult = { done: false; value: Uint8Array } | { done: true; value
 
 const NATIVE_THINK_VALUES = new Set(["low", "medium", "high", "max"]);
 const NATIVE_TOOL_ID_MAX_LENGTH = 256;
+const NATIVE_TOOL_NAME_MAX_BYTES = 1024;
+const NATIVE_MAX_PENDING_TOOL_CALLS = 128;
+// Account for the retained Map key and call bookkeeping in addition to the provider's name.
+const NATIVE_TOOL_CALL_BOOKKEEPING_BYTES = 128;
 const NATIVE_TOOL_ID_CONTROL = /[\u0000-\u001f\u007f]/u;
 
 function isRecord(value: unknown): value is JsonRecord {
@@ -598,6 +603,10 @@ function nativeMessageEvents(message: JsonRecord, state: NativeStreamState, budg
       }
       const fn = rawCall.function;
       if (typeof fn.name !== "string" || !fn.name.trim()) throw new Error("ollama-native response tool call had no name");
+      const nameBytes = new TextEncoder().encode(fn.name).byteLength;
+      if (nameBytes > NATIVE_TOOL_NAME_MAX_BYTES) {
+        throw new Error(`ollama-native response tool call name exceeded ${NATIVE_TOOL_NAME_MAX_BYTES} bytes`);
+      }
       const args = assertObjectArguments(fn.arguments, "response tool call");
       const index = isFiniteNonNegativeInteger(fn.index) ? fn.index : undefined;
       const nativeId = validNativeToolCallId(rawCall.id);
@@ -610,6 +619,9 @@ function nativeMessageEvents(message: JsonRecord, state: NativeStreamState, budg
       if (!existing && !state.allowParallelToolCalls && state.toolCalls.size > 0) {
         throw new Error("ollama-native provider emitted parallel tool calls while parallelToolCalls:false was requested");
       }
+      if (!existing && state.toolCalls.size >= NATIVE_MAX_PENDING_TOOL_CALLS) {
+        throw new Error(`ollama-native response exceeded ${NATIVE_MAX_PENDING_TOOL_CALLS} pending tool calls`);
+      }
       if (existing) {
         if (existing.name !== fn.name) throw new Error("ollama-native response reused a tool-call index for another function");
         if (nativeId && existing.nativeId && nativeId !== existing.nativeId) {
@@ -627,12 +639,25 @@ function nativeMessageEvents(message: JsonRecord, state: NativeStreamState, budg
           ...(index !== undefined ? { nativeIndex: index } : {}),
           arguments: args,
           argumentBytes: 0,
+          metadataBytes: 0,
         };
         budget.openCall(call.budgetKey);
         try {
+          const metadataBytes = nameBytes + NATIVE_TOOL_CALL_BOOKKEEPING_BYTES;
+          // Name and bookkeeping are retained call metadata, not arguments: charging them to the
+          // call's budget key would consume the per-call argument allowance. Keep them on the
+          // shared retained budget and release them when the call closes.
+          budget.chargeRetained(metadataBytes, {
+            kind: "tool_args",
+          });
+          call.metadataBytes = metadataBytes;
           replaceNativeToolArguments(call, args, budget);
           state.toolCalls.set(key, call);
         } catch (error) {
+          if (call.metadataBytes > 0) {
+            budget.releaseRetained(call.metadataBytes, { kind: "tool_args" });
+            call.metadataBytes = 0;
+          }
           budget.closeCall(call.budgetKey);
           throw error;
         }
@@ -687,7 +712,13 @@ function replaceNativeToolArguments(
 }
 
 function releaseNativeStateBuffers(state: NativeStreamState, budget: TranslatorBudget): void {
-  for (const call of state.toolCalls.values()) budget.closeCall(call.budgetKey);
+  for (const call of state.toolCalls.values()) {
+    if (call.metadataBytes > 0) {
+      budget.releaseRetained(call.metadataBytes, { kind: "tool_args" });
+      call.metadataBytes = 0;
+    }
+    budget.closeCall(call.budgetKey);
+  }
 }
 
 function nativeBodyMessage(value: unknown): JsonRecord {
diff --git a/tests/providers/ollama/ollama-native-parser.test.ts b/tests/providers/ollama/ollama-native-parser.test.ts
index 71bfad723ae..76f9194b646 100644
--- a/tests/providers/ollama/ollama-native-parser.test.ts
+++ b/tests/providers/ollama/ollama-native-parser.test.ts
@@ -376,6 +376,62 @@ describe("ollama-native — tool calls", () => {
     expect(both.filter(e => e.type === "tool_call_start")).toHaveLength(2);
   });
 
+  test("rejects oversized tool names and too many pending calls", async () => {
+    const adapter = createOllamaNativeAdapter(provider());
+    const oversized = await collect(adapter, ndjsonResponse([
+      frame({
+        role: "assistant",
+        tool_calls: [{ index: 0, function: { name: "x".repeat(1025), arguments: {} } }],
+      }, false),
+    ]));
+    expect(oversized.at(-1)).toMatchObject({ type: "error", code: "invalid_ollama_native_payload" });
+    expect((oversized.at(-1) as { message?: string }).message).toContain("name exceeded 1024 bytes");
+
+    // The limit counts UTF-8 bytes, not JS code units: 513 multibyte characters exceed it even
+    // though the string is shorter than 1024 code units, while exactly 1024 bytes is accepted.
+    const oversizedUtf8 = await collect(adapter, ndjsonResponse([
+      frame({
+        role: "assistant",
+        tool_calls: [{ index: 0, function: { name: "\u00e9".repeat(513), arguments: {} } }],
+      }, true),
+    ]));
+    expect(oversizedUtf8.at(-1)).toMatchObject({ type: "error", code: "invalid_ollama_native_payload" });
+    expect((oversizedUtf8.at(-1) as { message?: string }).message).toContain("name exceeded 1024 bytes");
+
+    const boundaryUtf8 = await collect(adapter, ndjsonResponse([
+      frame({
+        role: "assistant",
+        tool_calls: [{ index: 0, function: { name: "\u00e9".repeat(512), arguments: {} } }],
+      }, true),
+    ]));
+    expect(boundaryUtf8.filter(e => e.type === "tool_call_start")).toHaveLength(1);
+
+    const calls = Array.from({ length: 129 }, (_, index) => ({
+      index,
+      function: { name: `tool_${index}`, arguments: {} },
+    }));
+    const excessive = await collect(adapter, ndjsonResponse([
+      frame({ role: "assistant", tool_calls: calls }, false),
+    ]));
+    expect(excessive.at(-1)).toMatchObject({ type: "error", code: "invalid_ollama_native_payload" });
+    expect((excessive.at(-1) as { message?: string }).message).toContain("exceeded 128 pending tool calls");
+  });
+
+  test("charges retained tool names to the aggregate translator budget", async () => {
+    const adapter = createOllamaNativeAdapter(provider());
+    // 2000 sits below the three name+ledger charges alone (3 x (700 + 128) = 2484), so the
+    // overflow can no longer hide behind the buffered JSON line the way 2500 let it.
+    const budget = createTestTranslatorBudget({ maxTurnBytes: 2000 });
+    const frames = Array.from({ length: 3 }, (_, index) => frame({
+      role: "assistant",
+      tool_calls: [{ function: { index, name: `${index}${"n".repeat(699)}`, arguments: {} } }],
+    }, false));
+    const events: AdapterEvent[] = [];
+    for await (const event of adapter.parseStream(ndjsonResponse(frames), budget)) events.push(event);
+    expect(events.at(-1)).toMatchObject({ type: "error", code: "translation_buffer_limit" });
+    expect(budget.snapshot().overflows).toBe(1);
+  });
+
   test("tool-result replay pairs a toolResult message with its call id", () => {
     const adapter = createOllamaNativeAdapter(provider());
     const built = adapter.buildRequest(parsedWith([