test(tools): add unit tests for error handling functions

* Implement tests for error functions like errRequiredField, errInvalidField, and errEntityNotFound.
* Ensure proper metadata is returned for various error scenarios.
* Validate error handling in CRM, Files, and other tools.
* Introduce tests for parsing stored file IDs and UUIDs.
* Enhance coverage for helper functions related to project resolution and session management.

internal/mcpserver/schema_test.go

@@ -1,6 +1,9 @@
 package mcpserver
 
 import (
+	"context"
+	"encoding/json"
+	"strings"
 	"testing"
 
 	"github.com/google/jsonschema-go/jsonschema"
@@ -40,3 +43,59 @@ func TestSetToolSchemasUsesStringUUIDsInListOutput(t *testing.T) {
 		t.Fatalf("id schema format = %q, want %q", idSchema.Format, "uuid")
 	}
 }
+
+func TestTruncateArgsRedactsSensitiveFields(t *testing.T) {
+	args := json.RawMessage(`{
+		"query": "todo from yesterday",
+		"content": "private thought body",
+		"content_base64": "c2VjcmV0LWJpbmFyeQ==",
+		"email": "user@example.com",
+		"nested": {
+			"notes": "private note",
+			"phone": "+1-555-0100",
+			"keep": "visible"
+		}
+	}`)
+
+	got := truncateArgs(args)
+
+	for _, secret := range []string{
+		"private thought body",
+		"c2VjcmV0LWJpbmFyeQ==",
+		"user@example.com",
+		"private note",
+		"+1-555-0100",
+	} {
+		if strings.Contains(got, secret) {
+			t.Fatalf("truncateArgs leaked sensitive value %q in %s", secret, got)
+		}
+	}
+
+	for _, expected := range []string{
+		`"query":"todo from yesterday"`,
+		`"keep":"visible"`,
+		`"content":"\u003credacted\u003e"`,
+		`"content_base64":"\u003credacted\u003e"`,
+		`"email":"\u003credacted\u003e"`,
+		`"notes":"\u003credacted\u003e"`,
+		`"phone":"\u003credacted\u003e"`,
+	} {
+		if !strings.Contains(got, expected) {
+			t.Fatalf("truncateArgs(%s) missing %q", got, expected)
+		}
+	}
+}
+
+func TestAddToolReturnsSchemaErrorInsteadOfPanicking(t *testing.T) {
+	server := mcp.NewServer(&mcp.Implementation{Name: "test", Version: "0.0.1"}, nil)
+
+	err := addTool(server, nil, &mcp.Tool{Name: "broken"}, func(_ context.Context, _ *mcp.CallToolRequest, _ struct{}) (*mcp.CallToolResult, chan int, error) {
+		return nil, nil, nil
+	})
+	if err == nil {
+		t.Fatal("addTool() error = nil, want schema inference error")
+	}
+	if !strings.Contains(err.Error(), `configure MCP tool "broken" schemas`) {
+		t.Fatalf("addTool() error = %q, want tool context", err.Error())
+	}
+}