diff --git a/loop/agent.go b/loop/agent.go
index c103919..2c8eec9 100644
--- a/loop/agent.go
+++ b/loop/agent.go
@@ -26,6 +26,7 @@
 	"sketch.dev/claudetool/onstart"
 	"sketch.dev/experiment"
 	"sketch.dev/llm"
+	"sketch.dev/llm/ant"
 	"sketch.dev/llm/conversation"
 )
 
@@ -228,8 +229,8 @@
 	if a.TurnDuration != nil {
 		attrs = append(attrs, slog.Int64("turnDuration", a.TurnDuration.Nanoseconds()))
 	}
-	if a.ToolResult != "" {
-		attrs = append(attrs, slog.String("tool_result", a.ToolResult))
+	if len(a.ToolResult) > 0 {
+		attrs = append(attrs, slog.Any("tool_result", a.ToolResult))
 	}
 	if a.ToolError {
 		attrs = append(attrs, slog.Bool("tool_error", a.ToolError))
@@ -554,6 +555,33 @@
 	a.mu.Unlock()
 }
 
+// contentToString converts []llm.Content to a string, concatenating all text content and skipping non-text types.
+// If there's only one element in the array and it's a text type, it returns that text directly.
+// It also processes nested ToolResult arrays recursively.
+func contentToString(contents []llm.Content) string {
+	if len(contents) == 0 {
+		return ""
+	}
+
+	// If there's only one element and it's a text type, return it directly
+	if len(contents) == 1 && contents[0].Type == llm.ContentTypeText {
+		return contents[0].Text
+	}
+
+	// Otherwise, concatenate all text content
+	var result strings.Builder
+	for _, content := range contents {
+		if content.Type == llm.ContentTypeText {
+			result.WriteString(content.Text)
+		} else if content.Type == llm.ContentTypeToolResult && len(content.ToolResult) > 0 {
+			// Recursively process nested tool results
+			result.WriteString(contentToString(content.ToolResult))
+		}
+	}
+
+	return result.String()
+}
+
 // OnToolResult implements ant.Listener.
 func (a *Agent) OnToolResult(ctx context.Context, convo *conversation.Convo, toolID string, toolName string, toolInput json.RawMessage, content llm.Content, result *string, err error) {
 	// Remove the tool call from outstanding calls
@@ -564,7 +592,7 @@
 	m := AgentMessage{
 		Type:       ToolUseMessageType,
 		Content:    content.Text,
-		ToolResult: content.ToolResult,
+		ToolResult: contentToString(content.ToolResult),
 		ToolError:  content.ToolError,
 		ToolName:   toolName,
 		ToolInput:  string(toolInput),
@@ -879,7 +907,8 @@
 	// Add browser tools if enabled
 	// if experiment.Enabled("browser") {
 	if true {
-		bTools, browserCleanup := browse.RegisterBrowserTools(a.config.Context)
+		_, supportsScreenshots := a.config.Service.(*ant.Service)
+		bTools, browserCleanup := browse.RegisterBrowserTools(a.config.Context, supportsScreenshots)
 		// Add cleanup function to context cancel
 		go func() {
 			<-a.config.Context.Done()
@@ -943,13 +972,13 @@
   },
   "required": ["question", "responseOptions"]
 }`),
-		Run: func(ctx context.Context, input json.RawMessage) (string, error) {
+		Run: func(ctx context.Context, input json.RawMessage) ([]llm.Content, error) {
 			// The Run logic for "multiplchoice" tool is a no-op on the server.
 			// The UI will present a list of options for the user to select from,
 			// and that's it as far as "executing" the tool_use goes.
 			// When the user *does* select one of the presented options, that
 			// responseText gets sent as a chat message on behalf of the user.
-			return "end your turn and wait for the user to respond", nil
+			return llm.TextContent("end your turn and wait for the user to respond"), nil
 		},
 	}
 	return ret
@@ -997,28 +1026,28 @@
 	},
 	"required": ["title"]
 }`),
-		Run: func(ctx context.Context, input json.RawMessage) (string, error) {
+		Run: func(ctx context.Context, input json.RawMessage) ([]llm.Content, error) {
 			var params struct {
 				Title string `json:"title"`
 			}
 			if err := json.Unmarshal(input, &params); err != nil {
-				return "", err
+				return nil, err
 			}
 
 			// We don't allow changing the title once set to be consistent with the previous behavior
 			// and to prevent accidental title changes
 			t := a.Title()
 			if t != "" {
-				return "", fmt.Errorf("title already set to: %s", t)
+				return nil, fmt.Errorf("title already set to: %s", t)
 			}
 
 			if params.Title == "" {
-				return "", fmt.Errorf("title parameter cannot be empty")
+				return nil, fmt.Errorf("title parameter cannot be empty")
 			}
 
 			a.SetTitle(params.Title)
 			response := fmt.Sprintf("Title set to %q", params.Title)
-			return response, nil
+			return llm.TextContent(response), nil
 		},
 	}
 	return titleTool
@@ -1039,28 +1068,28 @@
 	},
 	"required": ["branch_name"]
 }`),
-		Run: func(ctx context.Context, input json.RawMessage) (string, error) {
+		Run: func(ctx context.Context, input json.RawMessage) ([]llm.Content, error) {
 			var params struct {
 				BranchName string `json:"branch_name"`
 			}
 			if err := json.Unmarshal(input, &params); err != nil {
-				return "", err
+				return nil, err
 			}
 
 			b := a.BranchName()
 			if b != "" {
-				return "", fmt.Errorf("branch already set to: %s", b)
+				return nil, fmt.Errorf("branch already set to: %s", b)
 			}
 
 			if params.BranchName == "" {
-				return "", fmt.Errorf("branch_name parameter cannot be empty")
+				return nil, fmt.Errorf("branch_name must not be empty")
 			}
 			if params.BranchName != cleanBranchName(params.BranchName) {
-				return "", fmt.Errorf("branch_name parameter must be alphanumeric hyphenated slug")
+				return nil, fmt.Errorf("branch_name parameter must be alphanumeric hyphenated slug")
 			}
 			branchName := "sketch/" + params.BranchName
 			if branchExists(a.workingDir, branchName) {
-				return "", fmt.Errorf("branch %q already exists; please choose a different branch name", branchName)
+				return nil, fmt.Errorf("branch %q already exists; please choose a different branch name", branchName)
 			}
 
 			a.SetBranch(branchName)
@@ -1074,7 +1103,7 @@
 				response += "\n\n" + styleHint
 			}
 
-			return response, nil
+			return llm.TextContent(response), nil
 		},
 	}
 	return preCommit
@@ -1089,11 +1118,6 @@
 	a.inbox <- msg
 }
 
-func (a *Agent) ToolResultMessage(ctx context.Context, toolCallID, msg string) {
-	a.pushToOutbox(ctx, AgentMessage{Type: UserMessageType, Content: msg, ToolCallId: toolCallID})
-	a.inbox <- msg
-}
-
 func (a *Agent) CancelToolUse(toolUseID string, cause error) error {
 	return a.convo.CancelToolUse(toolUseID, cause)
 }
@@ -1137,6 +1161,11 @@
 		m.Timestamp = time.Now()
 	}
 
+	// If this is a ToolUseMessage and ToolResult is set but Content is not, copy the ToolResult to Content
+	if m.Type == ToolUseMessageType && m.ToolResult != "" && m.Content == "" {
+		m.Content = m.ToolResult
+	}
+
 	// If this is an end-of-turn message, calculate the turn duration and add it to the message
 	if m.EndOfTurn && m.Type == AgentMessageType {
 		turnDuration := time.Since(a.startOfTurn)
diff --git a/loop/agent_test.go b/loop/agent_test.go
index 72e7ccb..ce44352 100644
--- a/loop/agent_test.go
+++ b/loop/agent_test.go
@@ -680,3 +680,117 @@
 		t.Errorf("Expected to eventually reach StateEndOfTurn, but never did")
 	}
 }
+
+func TestContentToString(t *testing.T) {
+	tests := []struct {
+		name     string
+		contents []llm.Content
+		want     string
+	}{
+		{
+			name:     "empty",
+			contents: []llm.Content{},
+			want:     "",
+		},
+		{
+			name: "single text content",
+			contents: []llm.Content{
+				{Type: llm.ContentTypeText, Text: "hello world"},
+			},
+			want: "hello world",
+		},
+		{
+			name: "multiple text content",
+			contents: []llm.Content{
+				{Type: llm.ContentTypeText, Text: "hello "},
+				{Type: llm.ContentTypeText, Text: "world"},
+			},
+			want: "hello world",
+		},
+		{
+			name: "mixed content types",
+			contents: []llm.Content{
+				{Type: llm.ContentTypeText, Text: "hello "},
+				{Type: llm.ContentTypeText, MediaType: "image/png", Data: "base64data"},
+				{Type: llm.ContentTypeText, Text: "world"},
+			},
+			want: "hello world",
+		},
+		{
+			name: "non-text content only",
+			contents: []llm.Content{
+				{Type: llm.ContentTypeToolUse, ToolName: "example"},
+			},
+			want: "",
+		},
+		{
+			name: "nested tool result",
+			contents: []llm.Content{
+				{Type: llm.ContentTypeText, Text: "outer "},
+				{Type: llm.ContentTypeToolResult, ToolResult: []llm.Content{
+					{Type: llm.ContentTypeText, Text: "inner"},
+				}},
+			},
+			want: "outer inner",
+		},
+		{
+			name: "deeply nested tool result",
+			contents: []llm.Content{
+				{Type: llm.ContentTypeToolResult, ToolResult: []llm.Content{
+					{Type: llm.ContentTypeToolResult, ToolResult: []llm.Content{
+						{Type: llm.ContentTypeText, Text: "deeply nested"},
+					}},
+				}},
+			},
+			want: "deeply nested",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := contentToString(tt.contents); got != tt.want {
+				t.Errorf("contentToString() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestPushToOutbox(t *testing.T) {
+	// Create a new agent
+	a := &Agent{
+		outstandingLLMCalls:  make(map[string]struct{}),
+		outstandingToolCalls: make(map[string]string),
+		stateMachine:         NewStateMachine(),
+		subscribers:          make([]chan *AgentMessage, 0),
+	}
+
+	// Create a channel to receive messages
+	messageCh := make(chan *AgentMessage, 1)
+
+	// Add the channel to the subscribers list
+	a.mu.Lock()
+	a.subscribers = append(a.subscribers, messageCh)
+	a.mu.Unlock()
+
+	// We need to set the text that would be produced by our modified contentToString function
+	resultText := "test resultnested result" // Directly set the expected output
+
+	// In a real-world scenario, this would be coming from a toolResult that contained nested content
+
+	m := AgentMessage{
+		Type:       ToolUseMessageType,
+		ToolResult: resultText,
+	}
+
+	// Push the message to the outbox
+	a.pushToOutbox(context.Background(), m)
+
+	// Receive the message from the subscriber
+	received := <-messageCh
+
+	// Check that the Content field contains the concatenated text from ToolResult
+	expected := "test resultnested result"
+	if received.Content != expected {
+		t.Errorf("Expected Content to be %q, got %q", expected, received.Content)
+	}
+}
diff --git a/loop/agent_user_cancel_test.go b/loop/agent_user_cancel_test.go
index 0e5eb43..ed7df1b 100644
--- a/loop/agent_user_cancel_test.go
+++ b/loop/agent_user_cancel_test.go
@@ -74,11 +74,14 @@
 
 		toolUseContents := []llm.Content{
 			{
-				Type:       llm.ContentTypeToolResult,
-				ToolUseID:  "tool1",
-				Text:       "",
-				ToolResult: "This is a tool result",
-				ToolError:  false,
+				Type:      llm.ContentTypeToolResult,
+				ToolUseID: "tool1",
+				Text:      "",
+				ToolResult: []llm.Content{{
+					Type: llm.ContentTypeText,
+					Text: "This is a tool result",
+				}},
+				ToolError: false,
 			},
 		}
 		toolUseResultsMsg := llm.Message{
@@ -344,10 +347,13 @@
 		}
 		canceledToolUseContents := []llm.Content{
 			{
-				Type:       llm.ContentTypeToolResult,
-				ToolUseID:  "tool1",
-				ToolError:  true,
-				ToolResult: "user canceled this tool_use",
+				Type:      llm.ContentTypeToolResult,
+				ToolUseID: "tool1",
+				ToolError: true,
+				ToolResult: []llm.Content{{
+					Type: llm.ContentTypeText,
+					Text: "user canceled this tool_use",
+				}},
 			},
 		}
 		canceledToolUseMsg := llm.Message{
@@ -424,11 +430,14 @@
 
 	toolUseContents := []llm.Content{
 		{
-			Type:       llm.ContentTypeToolResult,
-			ToolUseID:  "tool1",
-			Text:       "",
-			ToolResult: "This is a tool result",
-			ToolError:  false,
+			Type:      llm.ContentTypeToolResult,
+			ToolUseID: "tool1",
+			Text:      "",
+			ToolResult: []llm.Content{{
+				Type: llm.ContentTypeText,
+				Text: "This is a tool result",
+			}},
+			ToolError: false,
 		},
 	}
 	toolUseResponse := &llm.Response{
diff --git a/loop/donetool.go b/loop/donetool.go
index 4261a98..12db3b8 100644
--- a/loop/donetool.go
+++ b/loop/donetool.go
@@ -19,23 +19,23 @@
 		Name:        "done",
 		Description: doneDescription,
 		InputSchema: json.RawMessage(doneChecklistJSONSchema),
-		Run: func(ctx context.Context, input json.RawMessage) (string, error) {
+		Run: func(ctx context.Context, input json.RawMessage) ([]llm.Content, error) {
 			// Cannot be done with a messy git.
 			if err := codereview.RequireNormalGitState(ctx); err != nil {
-				return "", err
+				return nil, err
 			}
 			if err := codereview.RequireNoUncommittedChanges(ctx); err != nil {
-				return "", err
+				return nil, err
 			}
 			// Ensure that the current commit has been reviewed.
 			head, err := codereview.CurrentCommit(ctx)
 			if err == nil {
 				needsReview := !codereview.IsInitialCommit(head) && !codereview.HasReviewed(head)
 				if needsReview {
-					return "", fmt.Errorf("codereview tool has not been run for commit %v", head)
+					return nil, fmt.Errorf("codereview tool has not been run for commit %v", head)
 				}
 			}
-			return `Please ask the user to review your work. Be concise - users are more likely to read shorter comments.`, nil
+			return llm.TextContent("Please ask the user to review your work. Be concise - users are more likely to read shorter comments."), nil
 		},
 	}
 }
diff --git a/loop/testdata/agent_loop.httprr b/loop/testdata/agent_loop.httprr
index 64137c0..512e5d1 100644
--- a/loop/testdata/agent_loop.httprr
+++ b/loop/testdata/agent_loop.httprr
@@ -1,9 +1,9 @@
 httprr trace v1
-14275 2118
+14628 2230
 POST https://api.anthropic.com/v1/messages HTTP/1.1
 Host: api.anthropic.com
 User-Agent: Go-http-client/1.1
-Content-Length: 14077
+Content-Length: 14430
 Anthropic-Version: 2023-06-01
 Content-Type: application/json
 
@@ -350,6 +350,22 @@
    }
   },
   {
+   "name": "browser_scroll_into_view",
+   "description": "Scroll an element into view if it's not visible",
+   "input_schema": {
+    "type": "object",
+    "properties": {
+     "selector": {
+      "type": "string",
+      "description": "CSS selector for the element to scroll into view"
+     }
+    },
+    "required": [
+     "selector"
+    ]
+   }
+  },
+  {
    "name": "browser_screenshot",
    "description": "Take a screenshot of the page or a specific element",
    "input_schema": {
@@ -371,18 +387,18 @@
    }
   },
   {
-   "name": "browser_scroll_into_view",
-   "description": "Scroll an element into view if it's not visible",
+   "name": "browser_read_image",
+   "description": "Read an image file (such as a screenshot) and encode it for sending to the LLM",
    "input_schema": {
     "type": "object",
     "properties": {
-     "selector": {
+     "path": {
       "type": "string",
-      "description": "CSS selector for the element to scroll into view"
+      "description": "Path to the image file to read"
      }
     },
     "required": [
-     "selector"
+     "path"
     ]
    }
   },
@@ -448,24 +464,24 @@
 Anthropic-Organization-Id: 3c473a21-7208-450a-a9f8-80aebda45c1b
 Anthropic-Ratelimit-Input-Tokens-Limit: 200000
 Anthropic-Ratelimit-Input-Tokens-Remaining: 200000
-Anthropic-Ratelimit-Input-Tokens-Reset: 2025-05-09T22:32:28Z
+Anthropic-Ratelimit-Input-Tokens-Reset: 2025-05-10T13:34:48Z
 Anthropic-Ratelimit-Output-Tokens-Limit: 80000
 Anthropic-Ratelimit-Output-Tokens-Remaining: 80000
-Anthropic-Ratelimit-Output-Tokens-Reset: 2025-05-09T22:32:31Z
+Anthropic-Ratelimit-Output-Tokens-Reset: 2025-05-10T13:34:52Z
 Anthropic-Ratelimit-Requests-Limit: 4000
 Anthropic-Ratelimit-Requests-Remaining: 3999
-Anthropic-Ratelimit-Requests-Reset: 2025-05-09T22:32:27Z
+Anthropic-Ratelimit-Requests-Reset: 2025-05-10T13:34:47Z
 Anthropic-Ratelimit-Tokens-Limit: 280000
 Anthropic-Ratelimit-Tokens-Remaining: 280000
-Anthropic-Ratelimit-Tokens-Reset: 2025-05-09T22:32:28Z
+Anthropic-Ratelimit-Tokens-Reset: 2025-05-10T13:34:48Z
 Cf-Cache-Status: DYNAMIC
-Cf-Ray: 93d4a720b88fb976-SJC
+Cf-Ray: 93d9d0e80caa67fe-SJC
 Content-Type: application/json
-Date: Fri, 09 May 2025 22:32:31 GMT
-Request-Id: req_011CNxkUqzPtAV1N4dwqmCn8
+Date: Sat, 10 May 2025 13:34:52 GMT
+Request-Id: req_011CNywHj3Qrj3hEz9qFRVgK
 Server: cloudflare
 Strict-Transport-Security: max-age=31536000; includeSubDomains; preload
 Via: 1.1 google
 X-Robots-Tag: none
 
-{"id":"msg_01D6Uo6fKbA6VEwcrR1EJNDx","type":"message","role":"assistant","model":"claude-3-7-sonnet-20250219","content":[{"type":"text","text":"Here are the tools available to me:\n\n1. bash - Execute shell commands\n2. keyword_search - Find files with search terms\n3. think - Record thoughts or plans\n4. title - Set conversation title\n5. precommit - Create git branch for tracking work\n6. done - Mark task as complete with checklist\n7. codereview - Run automated code review\n8. multiplechoice - Present multiple-choice options\n9. browser_navigate - Navigate to URL\n10. browser_click - Click element with CSS selector\n11. browser_type - Type text into input element\n12. browser_wait_for - Wait for element to appear\n13. browser_get_text - Get text from element\n14. browser_eval - Run JavaScript in browser\n15. browser_screenshot - Take screenshot\n16. browser_scroll_into_view - Scroll element into view\n17. patch - Make precise text edits to files"}],"stop_reason":"end_turn","stop_sequence":null,"usage":{"input_tokens":4,"cache_creation_input_tokens":3294,"cache_read_input_tokens":0,"output_tokens":206}}
\ No newline at end of file
+{"id":"msg_014KGRNEmFdTUGqDQN7sRmzc","type":"message","role":"assistant","model":"claude-3-7-sonnet-20250219","content":[{"type":"text","text":"Here are the tools available to me:\n\n1. bash - Executes shell commands\n2. keyword_search - Searches files with given keywords\n3. think - For recording thoughts, notes, and plans\n4. title - Sets conversation title\n5. precommit - Creates git branches and provides commit message guidance\n6. done - Marks task completion with a checklist\n7. codereview - Runs automated code review\n8. multiplechoice - Presents multiple choice options to the user\n9. Browser tools:\n   - browser_navigate - Opens a URL\n   - browser_click - Clicks elements\n   - browser_type - Types text into elements\n   - browser_wait_for - Waits for elements\n   - browser_get_text - Gets text from elements\n   - browser_eval - Runs JavaScript in browser\n   - browser_scroll_into_view - Scrolls to elements\n   - browser_screenshot - Takes screenshots\n   - browser_read_image - Reads image files\n10. patch - Makes precise text modifications to files"}],"stop_reason":"end_turn","stop_sequence":null,"usage":{"input_tokens":4,"cache_creation_input_tokens":3376,"cache_read_input_tokens":0,"output_tokens":236}}
\ No newline at end of file