Export feature class to a TSV file with geometry in WKT format

TSVToolbox.pyt

import arcpy


class Toolbox(object):
    def __init__(self):
        self.label = "TSV Toolbox"
        self.alias = "TSV Toolbox"
        self.tools = [TSVTool]


class TSVTool(object):
    def __init__(self):
        self.label = "Export Features"
        self.description = """
        Export features to TSV file with geometry in WKT.
        The WKT is the last field in the TSV file.
        """
        self.canRunInBackground = True

    def getParameterInfo(self):
        paramInp = arcpy.Parameter(name="in_inp", displayName="Input Dataset", direction="Input", datatype="Table View",
                                   parameterType="Required")
        paramTSV = arcpy.Parameter(name="in_tsv", displayName="Output TSV File", direction="Output", datatype="File",
                                   parameterType="Required")
        paramSep = arcpy.Parameter(name="in_sep", displayName="Field Separator", direction="Input", datatype="String",
                                   parameterType="Required")
        paramSep.value = "tab"
        paramHdr = arcpy.Parameter(name="in_hdr", displayName="Write Header", direction="Input", datatype="Boolean",
                                   parameterType="Required")
        paramHdr.value = False
        return [paramInp, paramTSV, paramSep, paramHdr]

    def isLicensed(self):
        return True

    def updateParameters(self, parameters):
        return

    def updateMessages(self, parameters):
        return

    def asText(self, o):
        return o.encode('UTF-8', 'replace') if isinstance(o, unicode) else str(o)

    def execute(self, parameters, messages):
        fc = parameters[0].valueAsText
        tsv = parameters[1].valueAsText

        description = arcpy.Describe(fc)
        shape_name = description.shapeFieldName
        field_names = [field.name for field in description.fields]
        field_names.remove(shape_name)
        field_names.append(shape_name + "@WKT")

        sep = parameters[2].valueAsText
        sep = '\t' if sep == "tab" else sep[0]
        with open(tsv, 'wb') as f:
            if parameters[3].value:
                f.write(sep.join(field_names))
                f.write('\n')
            with arcpy.da.SearchCursor(fc, field_names) as cursor:
                for row in cursor:
                    f.write(sep.join([self.asText(r) for r in row]))
                    f.write('\n')
        return