diff --git a/packages/ai/src/protocols/utils/tool-stream.ts b/packages/ai/src/protocols/utils/tool-stream.ts
index 667c5d39679..1bb271f8899 100644
--- a/packages/ai/src/protocols/utils/tool-stream.ts
+++ b/packages/ai/src/protocols/utils/tool-stream.ts
@@ -84,8 +84,6 @@ const toolCall = (route: string, tool: PendingTool, inputOverride?: string) => {
               id: tool.id,
               name: tool.name,
               raw,
-              message: error.reason.message,
-              providerMetadata: tool.providerMetadata,
             }),
           ),
     ),
diff --git a/packages/ai/src/schema/events.ts b/packages/ai/src/schema/events.ts
index 74e2e10ea63..5be1c4cf900 100644
--- a/packages/ai/src/schema/events.ts
+++ b/packages/ai/src/schema/events.ts
@@ -150,14 +150,12 @@ export const ToolInputEnd = Schema.Struct({
 }).annotate({ identifier: "LLM.Event.ToolInputEnd" })
 export type ToolInputEnd = Schema.Schema.Type<typeof ToolInputEnd>
 
-/** A local tool call that could not be decoded. `raw` is diagnostic-only. */
+/** A local tool call whose final input could not be decoded. */
 export const ToolInputError = Schema.Struct({
   type: Schema.tag("tool-input-error"),
   id: ToolCallID,
   name: Schema.String,
   raw: Schema.String,
-  message: Schema.String,
-  providerMetadata: Schema.optional(ProviderMetadata),
 }).annotate({ identifier: "LLM.Event.ToolInputError" })
 export type ToolInputError = Schema.Schema.Type<typeof ToolInputError>
 
diff --git a/packages/ai/test/provider/openai-responses.test.ts b/packages/ai/test/provider/openai-responses.test.ts
index cde2a531dd0..3bfe72da146 100644
--- a/packages/ai/test/provider/openai-responses.test.ts
+++ b/packages/ai/test/provider/openai-responses.test.ts
@@ -1290,8 +1290,6 @@ describe("OpenAI Responses route", () => {
         id: "call_1",
         name: "lookup",
         raw: '{"query":"partial',
-        message: "Invalid JSON input for openai-responses tool call lookup",
-        providerMetadata: { openai: { itemId: "item_1" } },
       })
       expect(response.finishReason).toBe("tool-calls")
       expect(response.events.some(LLMEvent.is.toolCall)).toBeFalse()
diff --git a/packages/ai/test/response.test.ts b/packages/ai/test/response.test.ts
index f1b3c5db4f3..d3402be6c32 100644
--- a/packages/ai/test/response.test.ts
+++ b/packages/ai/test/response.test.ts
@@ -104,7 +104,6 @@ describe("LLMResponse reducer", () => {
         id: "call_1",
         name: "lookup",
         raw: '{"query":"partial',
-        message: "Invalid JSON input",
       }),
     ])
 
diff --git a/packages/ai/test/tool-stream.test.ts b/packages/ai/test/tool-stream.test.ts
index 95c1bb7b671..c02b57c4862 100644
--- a/packages/ai/test/tool-stream.test.ts
+++ b/packages/ai/test/tool-stream.test.ts
@@ -81,7 +81,6 @@ describe("ToolStream", () => {
             id: "call_1",
             name: "lookup",
             raw: '{"query":"partial',
-            message: "Invalid JSON input for test-route tool call lookup",
           },
         ],
       })
@@ -112,7 +111,6 @@ describe("ToolStream", () => {
             id: "call_invalid",
             name: "lookup",
             raw: '{"query":"partial',
-            message: "Invalid JSON input for test-route tool call lookup",
           },
         ],
       })
diff --git a/packages/core/src/aisdk.ts b/packages/core/src/aisdk.ts
index 2aacaa79395..f4f9b03f718 100644
--- a/packages/core/src/aisdk.ts
+++ b/packages/core/src/aisdk.ts
@@ -642,8 +642,6 @@ function streamPartEvents(
                   id: event.toolCallId,
                   name: event.toolName,
                   raw: event.input,
-                  message: error.reason.message,
-                  providerMetadata: providerMetadata(event.providerMetadata),
                 }),
               ]),
         ),
diff --git a/packages/core/src/session/runner/llm.ts b/packages/core/src/session/runner/llm.ts
index 7f129ed0459..dfb5de04781 100644
--- a/packages/core/src/session/runner/llm.ts
+++ b/packages/core/src/session/runner/llm.ts
@@ -259,7 +259,7 @@ const layer = Layer.effect(
                 step: currentStep,
               })
             }
-            yield* serialized(publisher.failAssistant(error, true))
+            yield* serialized(publisher.failAssistant(error))
           }
           // Provider error events only arrive from the stream, so the flag is final here.
           const providerFailed = publisher.hasProviderError()
@@ -280,7 +280,7 @@ const layer = Layer.effect(
           if (settled._tag === "Failure") yield* FiberSet.clear(toolFibers)
           if (userDeclined || streamInterrupted || toolsInterrupted) {
             yield* serialized(publisher.failUnsettledTools({ type: "aborted", message: "Tool execution interrupted" }))
-            yield* serialized(publisher.failAssistant({ type: "aborted", message: "Step interrupted" }, true))
+            yield* serialized(publisher.failAssistant({ type: "aborted", message: "Step interrupted" }))
           }
           // A settled tool fiber failure is one of two things. A defect from a tool
           // implementation becomes a failed tool call the model can read, and the step still
@@ -293,7 +293,7 @@ const layer = Layer.effect(
             const failure = infraError ?? Cause.squash(settledFailure)
             const error = toSessionError(failure)
             yield* serialized(publisher.failUnsettledTools(error))
-            if (infraError !== undefined) yield* serialized(publisher.failAssistant(error, true))
+            if (infraError !== undefined) yield* serialized(publisher.failAssistant(error))
           }
 
           // Fail unresolved calls before the terminal step event. Local calls have joined, so
@@ -321,13 +321,10 @@ const layer = Layer.effect(
               : false
           if (hostedResultMissing && !publisher.stepSettlement())
             yield* serialized(
-              publisher.failAssistant(
-                {
-                  type: "tool.result-missing",
-                  message: "Provider did not return a tool result",
-                },
-                true,
-              ),
+              publisher.failAssistant({
+                type: "tool.result-missing",
+                message: "Provider did not return a tool result",
+              }),
             )
 
           const stepFailure = publisher.stepFailure()
diff --git a/packages/core/src/session/runner/publish-llm-event.ts b/packages/core/src/session/runner/publish-llm-event.ts
index 96f4deb3fe1..1344d2627a7 100644
--- a/packages/core/src/session/runner/publish-llm-event.ts
+++ b/packages/core/src/session/runner/publish-llm-event.ts
@@ -262,11 +262,11 @@ export const createLLMEventPublisher = (events: Pick<EventV2.Interface, "publish
     return failed
   })
 
-  const failAssistant = Effect.fnUntraced(function* (error: SessionError.Error, replace = false) {
+  const failAssistant = Effect.fnUntraced(function* (error: SessionError.Error) {
     yield* flush()
     yield* failTools(error, "uncalled")
     yield* startAssistant()
-    if (replace || stepFailure === undefined) stepFailure = error
+    if (stepFailure === undefined) stepFailure = error
   })
 
   const publishStepFailure = Effect.fnUntraced(function* (details?: {
@@ -458,7 +458,7 @@ export const createLLMEventPublisher = (events: Pick<EventV2.Interface, "publish
         stepSettlement = { finish: event.reason, tokens: SessionUsage.tokens(event.usage) }
         if (event.reason === "content-filter") {
           providerFailed = true
-          yield* failAssistant({ type: "provider.content-filter", message: "Provider blocked the response" }, true)
+          yield* failAssistant({ type: "provider.content-filter", message: "Provider blocked the response" })
           return
         }
         return
@@ -466,7 +466,7 @@ export const createLLMEventPublisher = (events: Pick<EventV2.Interface, "publish
         return
       case "provider-error":
         providerFailed = true
-        yield* failAssistant({ type: "provider.unknown", message: event.message }, true)
+        yield* failAssistant({ type: "provider.unknown", message: event.message })
         return
     }
   })
diff --git a/packages/core/src/session/runner/to-llm-message.ts b/packages/core/src/session/runner/to-llm-message.ts
index 7aa52e53e30..1c875387d0b 100644
--- a/packages/core/src/session/runner/to-llm-message.ts
+++ b/packages/core/src/session/runner/to-llm-message.ts
@@ -137,11 +137,10 @@ const assistant = (message: SessionMessage.Assistant, model: ModelV2.Ref, provid
           ? [{ type: "text", text: item.text }]
           : []
     const reuseToolProviderMetadata =
-      sameModel &&
-      (message.error === undefined ||
-        (item.executed === true &&
-          (item.state.status === "completed" ||
-            (item.state.status === "error" && item.state.result !== undefined))))
+      reuseProviderMetadata ||
+      (sameModel &&
+        item.executed === true &&
+        (item.state.status === "completed" || (item.state.status === "error" && item.state.result !== undefined)))
     const call = toolCall(
       item,
       reuseToolProviderMetadata ? providerMetadata(providerMetadataKey, item.providerState) : undefined,
diff --git a/packages/core/test/aisdk.test.ts b/packages/core/test/aisdk.test.ts
index 2ab0a977faa..0bc16e8f597 100644
--- a/packages/core/test/aisdk.test.ts
+++ b/packages/core/test/aisdk.test.ts
@@ -296,7 +296,6 @@ it.effect("emits malformed AI SDK tool input without executing it", () =>
       id: "call_1",
       name: "lookup",
       raw,
-      message: "Invalid JSON input for aisdk tool call lookup",
     })
     expect(response.events.some(LLMEvent.is.toolInputEnd)).toBeTrue()
     expect(response.events.some(LLMEvent.is.toolCall)).toBeFalse()
diff --git a/packages/core/test/session-runner.test.ts b/packages/core/test/session-runner.test.ts
index c0361e8722b..e3297a54a12 100644
--- a/packages/core/test/session-runner.test.ts
+++ b/packages/core/test/session-runner.test.ts
@@ -4180,7 +4180,6 @@ describe("SessionRunnerLLM", () => {
             id: "call-malformed",
             name: "echo",
             raw,
-            message: "Invalid JSON input for test tool call echo",
           }),
           LLMEvent.stepFinish({ index: 0, reason: "tool-calls" }),
           LLMEvent.finish({ reason: "tool-calls" }),
@@ -4278,7 +4277,6 @@ describe("SessionRunnerLLM", () => {
             id: "call-malformed",
             name: "echo",
             raw: '{"text":"partial',
-            message: "Invalid JSON input for test tool call echo",
           }),
           LLMEvent.stepFinish({ index: 0, reason: "tool-calls" }),
           LLMEvent.finish({ reason: "tool-calls" }),
@@ -4321,7 +4319,6 @@ describe("SessionRunnerLLM", () => {
           id: "call-malformed",
           name: "echo",
           raw: '{"text":"partial',
-          message: "Invalid JSON input for test tool call echo",
         }),
         LLMEvent.stepFinish({ index: 0, reason: "tool-calls" }),
         LLMEvent.finish({ reason: "tool-calls" }),
@@ -4387,7 +4384,7 @@ describe("SessionRunnerLLM", () => {
     }),
   )
 
-  it.effect("replaces malformed input diagnosis with a later provider failure", () =>
+  it.effect("records a provider failure after malformed input", () =>
     Effect.gen(function* () {
       const session = yield* setup
       yield* admit(session, "Fail after malformed input")
@@ -4402,7 +4399,6 @@ describe("SessionRunnerLLM", () => {
           id: "call-malformed",
           name: "echo",
           raw: '{"text":"partial',
-          message: "Invalid JSON input for test tool call echo",
         }),
       ]).pipe(Stream.concat(Stream.fail(failure)))
 
@@ -4432,7 +4428,6 @@ describe("SessionRunnerLLM", () => {
           id,
           name: "echo",
           raw: '{"text":"partial',
-          message: "Invalid JSON input for test tool call echo",
         }),
         LLMEvent.stepFinish({ index: 0, reason: "tool-calls" }),
         LLMEvent.finish({ reason: "tool-calls" }),
@@ -4468,7 +4463,6 @@ describe("SessionRunnerLLM", () => {
           id,
           name: "echo",
           raw: '{"text":"partial',
-          message: "Invalid JSON input for test tool call echo",
         }),
         LLMEvent.stepFinish({ index: 0, reason: "tool-calls" }),
         LLMEvent.finish({ reason: "tool-calls" }),
@@ -4575,6 +4569,24 @@ describe("SessionRunnerLLM", () => {
     }),
   )
 
+  it.effect("preserves the provider failure when tool output persistence also fails", () =>
+    Effect.gen(function* () {
+      const session = yield* setup
+      yield* admit(session, "Storage fails while provider fails")
+      response = [
+        LLMEvent.stepStart({ index: 0 }),
+        LLMEvent.toolCall({ id: "call-store-provider-error", name: "storefail", input: {} }),
+        LLMEvent.providerError({ message: "Provider unavailable" }),
+      ]
+
+      expect(yield* session.resume(sessionID).pipe(Effect.exit)).toMatchObject({ _tag: "Failure" })
+
+      expect(requireAssistant(yield* session.context(sessionID))).toMatchObject({
+        error: { type: "provider.unknown", message: "Provider unavailable" },
+      })
+    }),
+  )
+
   it.effect("durably fails a hosted tool left unresolved at normal provider EOF", () =>
     Effect.gen(function* () {
       const session = yield* setup