Fix MCP invalid params and sensitive error disclosure

changelog.d/unreleased/1417.fixed.md

@@ -0,0 +1,17 @@
+---
+category: fixed
+issues:
+  - 1417
+affected:
+  - src/CodeIndex/Mcp/McpServer.cs
+  - src/CodeIndex/Mcp/McpToolHandlers.cs
+  - tests/CodeIndex.Tests/McpServerTests.cs
+---
+
+## English
+
+- **MCP tool argument type mismatches now return JSON-RPC invalid params (#1417)** — wrong JSON types such as a string `limit` now produce `-32602` with structured parameter details instead of falling through to an internal/tool failure.
+
+## 日本語
+
+- **MCP ツール引数の型不一致が JSON-RPC invalid params を返すようになりました (#1417)** — 文字列の `limit` など誤った JSON 型は、internal/tool failure に落ちず `-32602` と構造化されたパラメータ詳細を返します。

changelog.d/unreleased/1469.fixed.md

@@ -0,0 +1,16 @@
+---
+category: fixed
+issues:
+  - 1469
+affected:
+  - src/CodeIndex/Mcp/McpServer.cs
+  - tests/CodeIndex.Tests/McpServerTests.cs
+---
+
+## English
+
+- **MCP startup logs no longer expose the full DB path by default (#1469)** — the startup banner now logs only a sanitized DB filename unless `CDIDX_DEBUG=unsafe` is set.
+
+## 日本語
+
+- **MCP 起動ログが既定で完全な DB パスを公開しないようになりました (#1469)** — 起動バナーは `CDIDX_DEBUG=unsafe` が設定されていない限り、サニタイズ済みの DB ファイル名だけを記録します。

changelog.d/unreleased/1470.fixed.md

@@ -0,0 +1,16 @@
+---
+category: fixed
+issues:
+  - 1470
+affected:
+  - src/CodeIndex/Mcp/McpServer.cs
+  - tests/CodeIndex.Tests/McpServerTests.cs
+---
+
+## English
+
+- **MCP catch-all error responses now hide exception details by default (#1470)** — unexpected tool and loop failures return generic wire messages while preserving detailed diagnostics in stderr, with verbose responses limited to `CDIDX_DEBUG=unsafe`.
+
+## 日本語
+
+- **MCP catch-all エラー応答が既定で例外詳細を隠すようになりました (#1470)** — 予期しないツール/ループ失敗は wire 上では汎用メッセージを返し、詳細診断は stderr に残します。詳細応答は `CDIDX_DEBUG=unsafe` の場合だけ有効です。

src/CodeIndex/Mcp/McpServer.cs

@@ -157,6 +157,7 @@ public partial class McpServer : IDisposable
     internal const int DefaultMaxResponseBytes = 10 * 1024 * 1024;
     private const string MaxResponseBytesEnvVar = "CDIDX_MCP_RESPONSE_MAX_BYTES";
     private const string KeepAliveIntervalEnvironmentVariable = "CDIDX_MCP_KEEP_ALIVE_INTERVAL_S";
+    internal const string DebugEnvironmentVariable = "CDIDX_DEBUG";
     internal const int MaxJsonDepth = 32;
     internal const int MaxBatchRequestCount = 100;
     // Stdio buffer for the JSON-RPC loop. Sized to fit typical large MCP payloads (e.g. batch_query)
@@ -436,7 +437,7 @@ internal async Task RunAsync(IMcpTransport transport, CancellationToken cancella
 
         // Use stderr for logging so stdout stays clean for JSON-RPC
         // stdoutをJSON-RPC用にクリーンに保つため、ログはstderrに出力
-        ConsoleUi.TryWriteErrorLine($"[cdidx-mcp] Starting MCP server v{_version} (db: {_dbPath}, transport: {transport.Name} @ {transport.Endpoint}, max in-flight: {MaxConcurrency})");
+        ConsoleUi.TryWriteErrorLine($"[cdidx-mcp] Starting MCP server v{_version} (db: {FormatDbPathForLog(_dbPath)}, transport: {transport.Name} @ {transport.Endpoint}, max in-flight: {MaxConcurrency})");
 
         if (transport is HttpMcpTransport httpTransport)
         {
@@ -2143,11 +2144,25 @@ private async Task<JsonNode> HandleToolsCallAsync(JsonNode? id, JsonNode? callPa
             if (ValidateToolArguments(toolName, args) is JsonObject argumentError)
             {
                 metricsError = "invalid_argument";
-                response = CreateToolErrorResponse(id, argumentError["message"]!.GetValue<string>(),
-                    category: McpErrorEnvelope.CategoryInvalidArgument,
-                    suggestion: "Use exactly the argument names advertised by tools/list for this tool.",
-                    retrySafe: false,
-                    extraData: argumentError);
+                if (argumentError["jsonrpc_invalid_params"] is JsonValue invalidParamsMarker
+                    && invalidParamsMarker.TryGetValue<bool>(out var invalidParams)
+                    && invalidParams)
+                {
+                    argumentError.Remove("jsonrpc_invalid_params");
+                    response = CreateErrorResponse(hasId: true, id: id, code: -32602, message: argumentError["message"]!.GetValue<string>(),
+                        category: McpErrorEnvelope.CategoryInvalidArgument,
+                        suggestion: "Use the JSON types advertised by tools/list for this tool.",
+                        retrySafe: false,
+                        extraData: argumentError);
+                }
+                else
+                {
+                    response = CreateToolErrorResponse(id, argumentError["message"]!.GetValue<string>(),
+                        category: McpErrorEnvelope.CategoryInvalidArgument,
+                        suggestion: "Use exactly the argument names advertised by tools/list for this tool.",
+                        retrySafe: false,
+                        extraData: argumentError);
+                }
             }
             else if (ValidateCommonListArguments(args) is JsonObject listArgumentError)
             {
@@ -2556,6 +2571,28 @@ internal static string BuildUnknownNotificationLog(string method) =>
     internal static bool IsSupportedMcpLogLevel(string? level)
         => level is "debug" or "info" or "notice" or "warning" or "error" or "critical" or "alert" or "emergency";
 
+    internal static bool IsUnsafeDebugEnabled()
+        => string.Equals(Environment.GetEnvironmentVariable(DebugEnvironmentVariable), "unsafe", StringComparison.OrdinalIgnoreCase);
+
+    internal static string FormatDbPathForLog(string dbPath)
+    {
+        if (IsUnsafeDebugEnabled())
+            return dbPath;
+
+        try
+        {
+            var path = dbPath;
+            if (Uri.TryCreate(dbPath, UriKind.Absolute, out var uri) && uri.IsFile)
+                path = uri.LocalPath;
+            var fileName = Path.GetFileName(path);
+            return string.IsNullOrWhiteSpace(fileName) ? "(configured db)" : fileName;
+        }
+        catch
+        {
+            return "(configured db)";
+        }
+    }
+
     // Wire-safe error body for the tool catch-all. Mentions the tool and the
     // exception type so the client can branch (retry vs. surface to user)
     // while keeping bound values or matched content out of the response (#1530).
@@ -2569,6 +2606,8 @@ internal static bool IsSupportedMcpLogLevel(string? level)
     // #1530 で封じた ex.Message 漏れを再現させずに失敗詳細をクライアントへ届ける。
     internal static string BuildSanitizedToolErrorMessage(string toolName, Exception ex)
     {
+        if (!IsUnsafeDebugEnabled())
+            return $"Tool '{toolName}' failed. See cdidx server stderr for details.";
         if (ex is CodeIndexException codeIndexEx)
             return $"Error executing {toolName} ({ex.GetType().Name}) [{codeIndexEx.Code}/{codeIndexEx.Category}]{BuildPathFragment(codeIndexEx)}{BuildHintFragment(codeIndexEx)}. See cdidx server stderr for details.";
         return $"Error executing {toolName} ({ex.GetType().Name}). See cdidx server stderr for details.";
@@ -2579,6 +2618,8 @@ internal static string BuildSanitizedToolErrorMessage(string toolName, Exception
     // JSON-RPC ループ catch-all のワイヤー向け本文。理由はツール catch-all と同じ（#1530, #1580）。
     internal static string BuildSanitizedLoopErrorMessage(Exception ex)
     {
+        if (!IsUnsafeDebugEnabled())
+            return "Internal MCP error. See cdidx server stderr for details.";
         if (ex is CodeIndexException codeIndexEx)
             return $"Internal error ({ex.GetType().Name}) [{codeIndexEx.Code}/{codeIndexEx.Category}]{BuildPathFragment(codeIndexEx)}{BuildHintFragment(codeIndexEx)}. See cdidx server stderr for details.";
         return $"Internal error ({ex.GetType().Name}). See cdidx server stderr for details.";

src/CodeIndex/Mcp/McpToolHandlers.cs

@@ -386,9 +386,88 @@ private static List<string> ReadStringList(JsonNode? args, string propertyName)
             }
         }
 
+        if (ValidateToolArgumentTypes(toolName, obj) is JsonObject typeError)
+            return typeError;
+
         return null;
     }
 
+    private static JsonObject? ValidateToolArgumentTypes(string toolName, JsonObject args)
+    {
+        foreach (var property in args)
+        {
+            if (TryGetExpectedJsonType(toolName, property.Key, out var expected)
+                && !MatchesExpectedJsonType(property.Value, expected))
+            {
+                return new JsonObject
+                {
+                    ["message"] = $"Invalid type for argument '{property.Key}' on tool '{toolName}'. Expected {expected}.",
+                    ["tool"] = toolName,
+                    ["parameter"] = property.Key,
+                    ["expected"] = expected,
+                    ["actual"] = DescribeJsonType(property.Value),
+                    ["jsonrpc_invalid_params"] = true,
+                };
+            }
+        }
+
+        return null;
+    }
+
+    private static bool TryGetExpectedJsonType(string toolName, string argumentName, out string expected)
+    {
+        if (argumentName is "path" or "project" or "excludePaths" or "names")
+        {
+            expected = string.Empty;
+            return false;
+        }
+
+        expected = argumentName switch
+        {
+            "limit" or "offset" or "snippetLines" or "maxLineWidth" or "before" or "after" or
+                "focusLine" or "focusColumn" or "focusLength" or "startLine" or "endLine" or
+                "maxHops" or "maxDepth" or "depth" or "parallelism" => "integer",
+            "excludeTests" or "includeGenerated" or "rawQuery" or "noDedup" or "exactSubstring" or
+                "exactName" or "exact" or "prefix" or "countOnly" or "includeBody" or "lsp_compatible" or
+                "regex" or "withPaths" or "rebuild" or "dryRun" or "dry_run" or "force" or "optimize" => "boolean",
+            "query" or "lang" or "kind" or "format" or "rankBy" or "since" or "path" or "project" or
+                "solution" or "symbol" or "direction" or "groupBy" or "category" or "language" or
+                "description" or "context" or "toolInvocationContext" or "db" => "string",
+            "queries" => "array",
+            _ => string.Empty,
+        };
+
+        if (expected.Length == 0)
+            return false;
+
+        return true;
+    }
+
+    private static bool MatchesExpectedJsonType(JsonNode? node, string expected) => expected switch
+    {
+        "integer" => node is JsonValue value && value.TryGetValue<int>(out _),
+        "boolean" => node is JsonValue value && value.TryGetValue<bool>(out _),
+        "string" => node is JsonValue value && value.TryGetValue<string>(out _),
+        "array" => node is JsonArray,
+        _ => true,
+    };
+
+    private static string DescribeJsonType(JsonNode? node)
+    {
+        if (node is null)
+            return "null";
+        return node.GetValueKind() switch
+        {
+            JsonValueKind.String => "string",
+            JsonValueKind.Number => "number",
+            JsonValueKind.True or JsonValueKind.False => "boolean",
+            JsonValueKind.Array => "array",
+            JsonValueKind.Object => "object",
+            JsonValueKind.Null => "null",
+            _ => "unknown",
+        };
+    }
+
     private static bool IsKnownToolName(string toolName) => toolName switch
     {
         "search" or "definition" or "references" or "callers" or "callees" or "symbols" or