diff --git a/plugins/inspect/app/components/FunctionRow.vue b/plugins/inspect/app/components/FunctionRow.vue
index e684efe6..684e7b3f 100644
--- a/plugins/inspect/app/components/FunctionRow.vue
+++ b/plugins/inspect/app/components/FunctionRow.vue
@@ -1,7 +1,8 @@
 <script setup lang="ts">
 import type { RpcFunctionInfo } from '../connect'
 import ActionButton from '@antfu/design/components/Action/ActionButton.vue'
-import { computed, ref } from 'vue'
+import FeedbackTip from '@antfu/design/components/Feedback/FeedbackTip.vue'
+import { computed, ref, useId } from 'vue'
 import FunctionName from './FunctionName.vue'
 import JsonView from './JsonView.vue'
 
@@ -11,6 +12,7 @@ const props = defineProps<{
   results: Record<string, any>
   pending: Record<string, boolean>
   isStatic: boolean
+  invokeError?: string
 }>()
 
 const emit = defineEmits<{
@@ -19,6 +21,7 @@ const emit = defineEmits<{
 }>()
 
 const expanded = ref(false)
+const invokeErrorId = useId()
 
 const clickable = computed(() =>
   props.fn.invokable || !!props.fn.agent || props.fn.hasArgs || props.fn.hasReturns,
@@ -67,7 +70,25 @@ function toggle(): void {
         <div class="label">
           Invoke with positional args as a JSON array
         </div>
-        <textarea :value="argsInput[fn.name]" class="args" spellcheck="false" placeholder="[]" @input="emit('updateArgs', fn.name, ($event.target as HTMLTextAreaElement).value)" />
+        <textarea
+          :value="argsInput[fn.name]"
+          class="args"
+          spellcheck="false"
+          placeholder="[]"
+          :aria-invalid="!!invokeError"
+          :aria-describedby="invokeError ? invokeErrorId : undefined"
+          @input="emit('updateArgs', fn.name, ($event.target as HTMLTextAreaElement).value)"
+        />
+        <FeedbackTip
+          v-if="invokeError"
+          :id="invokeErrorId"
+          class="mt-2"
+          type="error"
+          icon="i-ph-warning-circle-duotone"
+          role="alert"
+        >
+          {{ invokeError }}
+        </FeedbackTip>
         <div style="margin-top: 8px; display: flex; gap: 8px; align-items: center;">
           <ActionButton
             variant="primary"
diff --git a/plugins/inspect/app/components/FunctionsView.stories.ts b/plugins/inspect/app/components/FunctionsView.stories.ts
index f5f9b612..a1908a08 100644
--- a/plugins/inspect/app/components/FunctionsView.stories.ts
+++ b/plugins/inspect/app/components/FunctionsView.stories.ts
@@ -1,4 +1,6 @@
 import type { Meta, StoryObj } from '@storybook/vue3-vite'
+import type { RpcFunctionInfo } from '../connect'
+import { expect, fn, userEvent, within } from 'storybook/test'
 import FunctionsView from './FunctionsView.vue'
 
 const meta = {
@@ -119,3 +121,71 @@ export const WithResultsAndPending: Story = {
     },
   },
 }
+
+const query: RpcFunctionInfo = {
+  name: 'audit:echo',
+  type: 'query',
+  jsonSerializable: true,
+  snapshot: false,
+  cacheable: false,
+  hasArgs: true,
+  hasReturns: false,
+  hasDump: false,
+  hasSetup: true,
+  hasHandler: true,
+  invokable: true,
+}
+
+export const InvalidArguments: Story = {
+  args: {
+    ...Default.args,
+    functions: [query],
+    onInvoke: fn(),
+  },
+  play: async ({ args, canvasElement }) => {
+    const canvas = within(canvasElement)
+    await userEvent.click(canvas.getByText('echo'))
+    const input = canvas.getByPlaceholderText('[]')
+    const invoke = canvas.getByRole('button', { name: 'Invoke' })
+
+    await userEvent.type(input, '{{')
+    await userEvent.click(invoke)
+    const error = canvas.getByRole('alert')
+    await expect(error).toHaveTextContent('Invalid JSON arguments:')
+    await expect(input).toHaveAttribute('aria-invalid', 'true')
+    await expect(input).toHaveAttribute('aria-describedby', error.id)
+    await expect(args.onInvoke).not.toHaveBeenCalled()
+
+    await userEvent.clear(input)
+    await expect(canvas.queryByRole('alert')).not.toBeInTheDocument()
+    await expect(input).toHaveAttribute('aria-invalid', 'false')
+    await userEvent.type(input, '[["recovered"]')
+    await userEvent.click(invoke)
+    await expect(args.onInvoke).toHaveBeenLastCalledWith(query, ['recovered'])
+
+    await userEvent.clear(input)
+    await userEvent.type(input, '42')
+    await userEvent.click(invoke)
+    await expect(args.onInvoke).toHaveBeenLastCalledWith(query, [42])
+  },
+}
+
+export const InvalidArgumentsAfterSuccess: Story = {
+  args: {
+    ...InvalidArguments.args,
+    results: {
+      'audit:echo': { ok: true, result: 'previous result', durationMs: 1 },
+    },
+    onInvoke: fn(),
+  },
+  play: async ({ args, canvasElement }) => {
+    const canvas = within(canvasElement)
+    await userEvent.click(canvas.getByText('echo'))
+    const input = canvas.getByPlaceholderText('[]')
+    await userEvent.type(input, '{{')
+    await userEvent.click(canvas.getByRole('button', { name: 'Invoke' }))
+    await expect(canvas.getByRole('alert')).toHaveTextContent('Invalid JSON arguments:')
+    await expect(canvas.getByText('"previous result"')).toBeVisible()
+    await expect(args.onInvoke).not.toHaveBeenCalled()
+  },
+}
diff --git a/plugins/inspect/app/components/FunctionsView.vue b/plugins/inspect/app/components/FunctionsView.vue
index f4025203..8254e65c 100644
--- a/plugins/inspect/app/components/FunctionsView.vue
+++ b/plugins/inspect/app/components/FunctionsView.vue
@@ -16,6 +16,7 @@ const emit = defineEmits<{
 
 const search = ref('')
 const argsInput = reactive<Record<string, string>>({})
+const invokeErrors = reactive<Record<string, string>>({})
 
 const filtered = computed(() => {
   const list = props.functions ?? []
@@ -38,10 +39,17 @@ function invoke(fn: RpcFunctionInfo): void {
     parsed = Array.isArray(raw) ? raw : [raw]
   }
   catch (e) {
-    throw new Error(`Invalid JSON args: ${(e as Error).message}`)
+    invokeErrors[fn.name] = `Invalid JSON arguments: ${(e as Error).message}`
+    return
   }
+  delete invokeErrors[fn.name]
   emit('invoke', fn, parsed)
 }
+
+function updateArgs(name: string, value: string): void {
+  argsInput[name] = value
+  delete invokeErrors[name]
+}
 </script>
 
 <template>
@@ -70,11 +78,12 @@ function invoke(fn: RpcFunctionInfo): void {
         :key="fn.name"
         :fn="fn"
         :args-input="argsInput"
+        :invoke-error="invokeErrors[fn.name]"
         :results="results"
         :pending="pending"
         :is-static="isStatic"
         @invoke="invoke"
-        @update-args="(n, v) => argsInput[n] = v"
+        @update-args="updateArgs"
       />
     </div>
   </div>