test: add tool name validation tests for Anthropic API compliance

Reflection-based tests verify all McpServerTool names match
^[a-zA-Z0-9_-]{1,64}$ and contain no dots, preventing regressions.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

PaperlessMCP.Tests/Tools/ToolNamingTests.cs

@@ -0,0 +1,53 @@
+using System.Reflection;
+using System.Text.RegularExpressions;
+using FluentAssertions;
+using ModelContextProtocol.Server;
+using Xunit;
+
+namespace PaperlessMCP.Tests.Tools;
+
+public class ToolNamingTests
+{
+    private static readonly Regex AnthropicToolNamePattern = new("^[a-zA-Z0-9_-]{1,64}$");
+
+    [Fact]
+    public void AllToolNames_ShouldMatchAnthropicApiNamingRules()
+    {
+        var toolAssembly = typeof(PaperlessMCP.Tools.HealthTools).Assembly;
+
+        var toolNames = toolAssembly.GetTypes()
+            .SelectMany(t => t.GetMethods(BindingFlags.Public | BindingFlags.Static | BindingFlags.Instance))
+            .SelectMany(m => m.GetCustomAttributes<McpServerToolAttribute>())
+            .Where(a => a.Name is not null)
+            .Select(a => a.Name!)
+            .ToList();
+
+        toolNames.Should().NotBeEmpty("expected to find at least one McpServerTool attribute");
+
+        var violations = toolNames
+            .Where(name => !AnthropicToolNamePattern.IsMatch(name))
+            .ToList();
+
+        violations.Should().BeEmpty(
+            "tool names must match ^[a-zA-Z0-9_-]{{1,64}}$ per Anthropic API rules, " +
+            $"but found: {string.Join(", ", violations)}");
+    }
+
+    [Fact]
+    public void AllToolNames_ShouldNotContainDots()
+    {
+        var toolAssembly = typeof(PaperlessMCP.Tools.HealthTools).Assembly;
+
+        var toolNames = toolAssembly.GetTypes()
+            .SelectMany(t => t.GetMethods(BindingFlags.Public | BindingFlags.Static | BindingFlags.Instance))
+            .SelectMany(m => m.GetCustomAttributes<McpServerToolAttribute>())
+            .Where(a => a.Name is not null)
+            .Select(a => a.Name!)
+            .ToList();
+
+        var dotNames = toolNames.Where(name => name.Contains('.')).ToList();
+
+        dotNames.Should().BeEmpty(
+            $"dots are not allowed in tool names, but found: {string.Join(", ", dotNames)}");
+    }
+}