diff --git a/loop/donetool.go b/loop/donetool.go
new file mode 100644
index 0000000..c02e5a5
--- /dev/null
+++ b/loop/donetool.go
@@ -0,0 +1,112 @@
+package loop
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+
+	"sketch.dev/ant"
+	"sketch.dev/claudetool"
+)
+
+// makeDoneTool creates a tool that provides a checklist to the agent. There
+// are some duplicative instructions here and in the system prompt, and it's
+// not as reliable as it could be. Historically, we've found that Claude ignores
+// the tool results here, so we don't tell the tool to say "hey, really check this"
+// at the moment, though we've tried.
+func makeDoneTool(codereview *claudetool.CodeReviewer, gitUsername, gitEmail string) *ant.Tool {
+	return &ant.Tool{
+		Name:        "done",
+		Description: `Use this tool when you have achieved the user's goal. The parameters form a checklist which you should evaluate.`,
+		InputSchema: json.RawMessage(doneChecklistJSONSchema(gitUsername, gitEmail)),
+		Run: func(ctx context.Context, input json.RawMessage) (string, error) {
+			// Cannot be done with a messy git.
+			if err := codereview.RequireNormalGitState(ctx); err != nil {
+				return "", err
+			}
+			if err := codereview.RequireNoUncommittedChanges(ctx); err != nil {
+				return "", 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 `Please ask the user to review your work. Be concise - users are more likely to read shorter comments.`, nil
+		},
+	}
+}
+
+func doneChecklistJSONSchema(gitUsername, gitEmail string) string {
+	gitCommitDescription := fmt.Sprintf(`Create git commits for any code changes you made. Match the style of recent commit messages. Include 'Co-Authored-By: sketch' and the original user prompt. Use GIT_AUTHOR_NAME="%s" GIT_AUTHOR_EMAIL="%s" (not git config).`,
+		gitUsername, gitEmail)
+	desc, err := json.Marshal(gitCommitDescription)
+	if err != nil {
+		panic(err)
+	}
+	return doneChecklistJSONSchemaPrefix + string(desc) + doneChecklistJSONSchemaSuffix
+}
+
+// TODO: this is ugly, maybe JSON-encode a deeply nested map[string]any instead? also ugly.
+const (
+	doneChecklistJSONSchemaPrefix = `{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "title": "Checklist",
+  "description": "A schema for tracking checklist items with status and comments",
+  "type": "object",
+  "required": ["checklist_items"],
+  "properties": {
+    "checklist_items": {
+      "type": "object",
+      "description": "Collection of checklist items",
+      "properties": {
+        "wrote_tests": {
+          "$ref": "#/definitions/checklistItem",
+          "description": "If code was changed, tests were written or updated."
+        },
+        "passes_tests": {
+          "$ref": "#/definitions/checklistItem",
+          "description": "If any commits were made, tests pass."
+        },
+        "code_reviewed": {
+          "$ref": "#/definitions/checklistItem",
+          "description": "If any commits were made, the codereview tool was run and its output was addressed."
+        },
+        "git_commit": {
+          "$ref": "#/definitions/checklistItem",
+          "description": `
+
+	doneChecklistJSONSchemaSuffix = `
+		}
+      },
+      "additionalProperties": {
+        "$ref": "#/definitions/checklistItem"
+      }
+    }
+  },
+  "definitions": {
+    "checklistItem": {
+      "type": "object",
+      "required": ["status"],
+      "properties": {
+        "status": {
+          "type": "string",
+          "description": "Current status of the checklist item",
+          "enum": ["yes", "no", "not applicable", "other"]
+        },
+        "description": {
+          "type": "string",
+          "description": "Description of what this checklist item verifies"
+        },
+        "comments": {
+          "type": "string",
+          "description": "Additional comments or context for this checklist item"
+        }
+      }
+    }
+  }
+}`
+)