diff --git a/src/agent/Agent.zig b/src/agent/Agent.zig
index 090f33a1..88de3bf7 100644
--- a/src/agent/Agent.zig
+++ b/src/agent/Agent.zig
@@ -36,7 +36,7 @@ const CDPNode = @import("../cdp/Node.zig");
 const Terminal = @import("Terminal.zig");
 const SlashCommand = @import("SlashCommand.zig");
 const settings = @import("settings.zig");
-const truncateUtf8 = @import("../string.zig").truncateUtf8;
+const string = @import("../string.zig");
 
 const Agent = @This();
 
@@ -186,7 +186,7 @@ fn reconcileModel(
     var arena: std.heap.ArenaAllocator = .init(allocator);
     defer arena.deinit();
     const ids: []const []const u8 = zenai.provider.listChatModelIds(allocator, arena.allocator(), llm.provider, llm.key, base_url) catch &.{};
-    if (ids.len == 0 or containsString(ids, desired)) return .{ .use = try allocator.dupe(u8, desired) };
+    if (ids.len == 0 or string.isOneOf(desired, ids)) return .{ .use = try allocator.dupe(u8, desired) };
 
     if (!explicit) {
         if (llm.provider != .ollama) return .{ .use = try allocator.dupe(u8, desired) };
@@ -684,7 +684,7 @@ fn handleVerbosity(self: *Agent, rest: []const u8) void {
         return;
     }
     const level = std.meta.stringToEnum(Config.AgentVerbosity, rest) orelse {
-        self.terminal.printError("usage: /verbosity <low|medium|high> (got {s})", .{rest});
+        self.terminal.printError("usage: /verbosity " ++ Config.tagHint(Config.AgentVerbosity) ++ " (got {s})", .{rest});
         return;
     };
     self.terminal.verbosity = level;
@@ -697,7 +697,7 @@ fn handleEffort(self: *Agent, rest: []const u8) void {
         return;
     }
     const level = std.meta.stringToEnum(Config.Effort, rest) orelse {
-        self.terminal.printError("usage: /effort <none|minimal|low|medium|high|xhigh> (got {s})", .{rest});
+        self.terminal.printError("usage: /effort " ++ Config.tagHint(Config.Effort) ++ " (got {s})", .{rest});
         return;
     };
     self.effort = level;
@@ -788,7 +788,7 @@ fn handleModel(self: *Agent, _: std.mem.Allocator, rest: []const u8) void {
     }
     const ids = completionModels(self, self.allocator);
     // Empty list = fetch failed or unlisted local models; can't confirm, so allow.
-    if (ids.len != 0 and !containsString(ids, trimmed)) {
+    if (ids.len != 0 and !string.isOneOf(trimmed, ids)) {
         self.terminal.printError("unknown model: {s} (Tab to list)", .{trimmed});
         return;
     }
@@ -797,13 +797,6 @@ fn handleModel(self: *Agent, _: std.mem.Allocator, rest: []const u8) void {
     };
 }
 
-fn containsString(haystack: []const []const u8, needle: []const u8) bool {
-    for (haystack) |s| {
-        if (std.mem.eql(u8, s, needle)) return true;
-    }
-    return false;
-}
-
 /// Persist the current provider/model/effort/verbosity to `.lp-agent.zon` and report it
 /// as "<label>: <value>", appending "(saved to …)" when the write succeeds. With no
 /// model credentials it persists `provider = null` only when that's an intentional
@@ -1254,11 +1247,11 @@ fn printSlashHelp(self: *Agent, arena: std.mem.Allocator, target: []const u8) vo
             .help => self.terminal.printInfo("/help [name] — show help for a command, or list all when [name] is omitted", .{}),
             .quit => self.terminal.printInfo("/quit — exit the REPL", .{}),
             .verbosity => self.terminal.printInfo(
-                "/verbosity <low|medium|high> — set REPL agent verbosity (currently: {s}). Bare /verbosity prints the level.",
+                "/verbosity " ++ Config.tagHint(Config.AgentVerbosity) ++ " — set REPL agent verbosity (currently: {s}). Bare /verbosity prints the level.",
                 .{@tagName(self.terminal.verbosity)},
             ),
             .effort => self.terminal.printInfo(
-                "/effort <none|minimal|low|medium|high|xhigh> — set per-turn reasoning effort (currently: {s}); saved to {s}. Bare /effort prints the level.",
+                "/effort " ++ Config.tagHint(Config.Effort) ++ " — set per-turn reasoning effort (currently: {s}); saved to {s}. Bare /effort prints the level.",
                 .{ @tagName(self.effort), settings.remembered_path },
             ),
             .usage => self.terminal.printInfo(
@@ -1744,7 +1737,7 @@ const tool_output_max_bytes: usize = 1 * 1024 * 1024;
 
 fn capToolOutput(allocator: std.mem.Allocator, output: []const u8) []const u8 {
     if (output.len <= tool_output_max_bytes) return output;
-    const prefix = truncateUtf8(output, tool_output_max_bytes);
+    const prefix = string.truncateUtf8(output, tool_output_max_bytes);
     var suffix_buf: [64]u8 = undefined;
     const suffix = std.fmt.bufPrint(&suffix_buf, "\n...[truncated, original {d} bytes]", .{output.len}) catch return prefix;
     return std.mem.concat(allocator, u8, &.{ prefix, suffix }) catch prefix;
diff --git a/src/script/Schema.zig b/src/script/Schema.zig
index ebb5985f..3aeebc09 100644
--- a/src/script/Schema.zig
+++ b/src/script/Schema.zig
@@ -24,6 +24,7 @@ const std = @import("std");
 const lp = @import("lightpanda");
 const browser_tools = lp.tools;
 const BrowserTool = browser_tools.Tool;
+const string = @import("../string.zig");
 
 const Schema = @This();
 
@@ -405,7 +406,7 @@ fn buildHints(arena: std.mem.Allocator, required: []const []const u8, fields: []
     if (fields.len == 0 and required.len == 0) return &.{};
     var optional_count: usize = 0;
     for (fields) |f| {
-        if (!containsName(required, f.name)) optional_count += 1;
+        if (!string.isOneOf(f.name, required)) optional_count += 1;
     }
     const out = try arena.alloc(HintSlot, required.len + optional_count);
     var idx: usize = 0;
@@ -419,7 +420,7 @@ fn buildHints(arena: std.mem.Allocator, required: []const []const u8, fields: []
         idx += 1;
     }
     for (fields) |f| {
-        if (containsName(required, f.name)) continue;
+        if (string.isOneOf(f.name, required)) continue;
         out[idx] = .{
             .name = f.name,
             .required = false,
@@ -430,11 +431,6 @@ fn buildHints(arena: std.mem.Allocator, required: []const []const u8, fields: []
     return out;
 }
 
-fn containsName(names: []const []const u8, target: []const u8) bool {
-    for (names) |n| if (std.mem.eql(u8, n, target)) return true;
-    return false;
-}
-
 fn fieldTypeOf(value: std.json.Value) FieldType {
     if (value != .object) return .other;
     const ty = value.object.get("type") orelse return .other;
diff --git a/src/string.zig b/src/string.zig
index 24bfe482..26961eb0 100644
--- a/src/string.zig
+++ b/src/string.zig
@@ -311,6 +311,13 @@ pub fn isAllWhitespace(text: []const u8) bool {
     } else true;
 }
 
+/// True when `needle` is byte-equal to one of the strings in `haystack`.
+pub fn isOneOf(needle: []const u8, haystack: []const []const u8) bool {
+    return for (haystack) |s| {
+        if (std.mem.eql(u8, s, needle)) break true;
+    } else false;
+}
+
 /// Largest prefix of `bytes` whose length is at most `max_bytes` and
 /// ends on a UTF-8 codepoint boundary. Invalid sequences count as one
 /// byte each so the function never loops.