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mcp: fix multi-select enum elicitation

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This commit is contained in:
Maciek Kisiel 2026-02-16 10:55:54 +00:00 • committed by Maciej Kisiel
commit 40475813dd
2 changed files with 160 additions and 34 deletions
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62
mcp/client.go
View file

@ -710,8 +710,10 @@ func validateElicitProperty(propName string, propSchema *jsonschema.Schema) erro
return validateElicitNumberProperty(propName, propSchema)
case "boolean":
return validateElicitBooleanProperty(propName, propSchema)
case "array":
return validateElicitArrayProperty(propName, propSchema)
default:
return fmt.Errorf("elicit schema property %q has unsupported type %q, only string, number, integer, and boolean are allowed", propName, propSchema.Type)
return fmt.Errorf("elicit schema property %q has unsupported type %q, only string, number, integer, boolean, and array are allowed", propName, propSchema.Type)
}
}
@ -724,7 +726,7 @@ func validateElicitStringProperty(propName string, propSchema *jsonschema.Schema
return fmt.Errorf("elicit schema property %q has enum values but type is %q, enums are only supported for string type", propName, propSchema.Type)
}
// Enum values themselves are validated by the JSON schema library
// Validate enumNames if present - must match enum length
// Validate legacy enumNames if present - must match enum length.
if propSchema.Extra != nil {
if enumNamesRaw, exists := propSchema.Extra["enumNames"]; exists {
// Type check enumNames - should be a slice
@ -739,6 +741,15 @@ func validateElicitStringProperty(propName string, propSchema *jsonschema.Schema
}
return nil
}
// Handle new style of titled enums.
if propSchema.OneOf != nil {
for _, entry := range propSchema.OneOf {
if err := validateTitledEnumEntry(entry); err != nil {
return fmt.Errorf("elicit schema property %q oneOf has invalid entry: %v", propName, err)
}
}
return nil
}
// Validate format if specified - only specific formats are allowed
if propSchema.Format != "" {
@ -791,6 +802,53 @@ func validateElicitNumberProperty(propName string, propSchema *jsonschema.Schema
return nil
}
// validateElicitArrayProperty validates multi-select enum properties.
func validateElicitArrayProperty(propName string, propSchema *jsonschema.Schema) error {
if propSchema.Items == nil {
return fmt.Errorf("elicit schema property %q is array but missing 'items' definition", propName)
}
items := propSchema.Items
switch items.Type {
case "string":
// Untitled enums.
if items.Enum == nil {
return fmt.Errorf("elicit schema property %q items must specify enum for untitled enums", propName)
}
return nil
case "":
// Titled enums.
if len(items.AnyOf) == 0 {
return fmt.Errorf("elicit schema property %q items must specify anyOf for titled enums", propName)
}
for _, entry := range items.AnyOf {
if err := validateTitledEnumEntry(entry); err != nil {
return fmt.Errorf("elicit schema property %q items has invalid entry: %v", propName, err)
}
}
return nil
default:
return fmt.Errorf("elicit schema property %q items have unsupported type %q", propName, items.Type)
}
}
func validateTitledEnumEntry(entry *jsonschema.Schema) error {
if entry.Const == nil {
return fmt.Errorf("const is required for titled enum entries")
}
constVal, ok := (*entry.Const).(string)
if !ok {
return fmt.Errorf("const must be a string for titled enum entries")
}
if constVal == "" {
return fmt.Errorf("const cannot be empty for titled enum entries")
}
if entry.Title == "" {
return fmt.Errorf("title is required for titled enum entries")
}
return nil
}
// validateElicitBooleanProperty validates boolean-type properties.
func validateElicitBooleanProperty(propName string, propSchema *jsonschema.Schema) error {
return validateDefaultProperty[bool](propName, propSchema)

142
mcp/mcp_test.go
View file

@ -1095,7 +1095,7 @@ func TestElicitationSchemaValidation(t *testing.T) {
},
},
{
name: "string enum",
name: "single select untitled enum",
schema: &jsonschema.Schema{
Type: "object",
Properties: map[string]*jsonschema.Schema{
@ -1111,7 +1111,7 @@ func TestElicitationSchemaValidation(t *testing.T) {
},
},
{
name: "enum with matching enumNames",
name: "legacy titled enum",
schema: &jsonschema.Schema{
Type: "object",
Properties: map[string]*jsonschema.Schema{
@ -1130,7 +1130,7 @@ func TestElicitationSchemaValidation(t *testing.T) {
},
},
{
name: "enum with enum schema",
name: "single select titled enum",
schema: &jsonschema.Schema{
Type: "object",
Properties: map[string]*jsonschema.Schema{
@ -1138,22 +1138,62 @@ func TestElicitationSchemaValidation(t *testing.T) {
Type: "string",
OneOf: []*jsonschema.Schema{
{
Const: anyPtr(map[string]string{
"const": "high",
"title": "High Priority",
}),
Const: anyPtr("high"),
Title: "High Priority",
},
{
Const: anyPtr(map[string]string{
"const": "medium",
"title": "Medium Priority",
}),
Const: anyPtr("medium"),
Title: "Medium Priority",
},
{
Const: anyPtr(map[string]string{
"const": "low",
"title": "Low Priority",
}),
Const: anyPtr("low"),
Title: "Low Priority",
},
},
},
},
},
},
{
name: "multi select untitled enum",
schema: &jsonschema.Schema{
Type: "object",
Properties: map[string]*jsonschema.Schema{
"status": {
Type: "array",
Items: &jsonschema.Schema{
Type: "string",
Enum: []any{
"active",
"inactive",
"pending",
},
},
},
},
},
},
{
name: "multi select titled enum",
schema: &jsonschema.Schema{
Type: "object",
Properties: map[string]*jsonschema.Schema{
"priority": {
Type: "array",
Items: &jsonschema.Schema{
AnyOf: []*jsonschema.Schema{
{
Const: anyPtr("high"),
Title: "High Priority",
},
{
Const: anyPtr("medium"),
Title: "Medium Priority",
},
{
Const: anyPtr("low"),
Title: "Low Priority",
},
},
},
},
@ -1210,17 +1250,7 @@ func TestElicitationSchemaValidation(t *testing.T) {
"config": {Type: "object"},
},
},
expectedError: "elicit schema property \"config\" has unsupported type \"object\", only string, number, integer, and boolean are allowed",
},
{
name: "array property",
schema: &jsonschema.Schema{
Type: "object",
Properties: map[string]*jsonschema.Schema{
"tags": {Type: "array", Items: &jsonschema.Schema{Type: "string"}},
},
},
expectedError: "elicit schema property \"tags\" has unsupported type \"array\", only string, number, integer, and boolean are allowed",
expectedError: "elicit schema property \"config\" has unsupported type \"object\", only string, number, integer, boolean, and array are allowed",
},
{
name: "array without items",
@ -1230,7 +1260,27 @@ func TestElicitationSchemaValidation(t *testing.T) {
"items": {Type: "array"},
},
},
expectedError: "elicit schema property \"items\" has unsupported type \"array\", only string, number, integer, and boolean are allowed",
expectedError: "elicit schema property \"items\" is array but missing 'items' definition",
},
{
name: "array with integer items",
schema: &jsonschema.Schema{
Type: "object",
Properties: map[string]*jsonschema.Schema{
"items": {Type: "array", Items: &jsonschema.Schema{Type: "integer"}},
},
},
expectedError: "elicit schema property \"items\" items have unsupported type \"integer\"",
},
{
name: "array of generic strings",
schema: &jsonschema.Schema{
Type: "object",
Properties: map[string]*jsonschema.Schema{
"items": {Type: "array", Items: &jsonschema.Schema{Type: "string"}},
},
},
expectedError: "elicit schema property \"items\" items must specify enum for untitled enums",
},
{
name: "unsupported string format",
@ -1385,7 +1435,29 @@ func TestElicitationSchemaValidation(t *testing.T) {
},
},
},
expectedError: "elicit schema property \"priority\" has unsupported type \"\", only string, number, integer, and boolean are allowed",
expectedError: "elicit schema property \"priority\" has unsupported type \"\", only string, number, integer, boolean, and array are allowed",
},
{
name: "titled enum without const",
schema: &jsonschema.Schema{
Type: "object",
Properties: map[string]*jsonschema.Schema{
"priority": {
Type: "string",
OneOf: []*jsonschema.Schema{
{
Const: anyPtr("high"),
Title: "High Priority",
},
{
Type: "string",
Title: "Other Priority",
},
},
},
},
},
expectedError: "elicit schema property \"priority\" oneOf has invalid entry: const is required for titled enum entries",
},
{
name: "untyped property",
@ -1395,7 +1467,7 @@ func TestElicitationSchemaValidation(t *testing.T) {
"data": {},
},
},
expectedError: "elicit schema property \"data\" has unsupported type \"\", only string, number, integer, and boolean are allowed",
expectedError: "elicit schema property \"data\" has unsupported type \"\", only string, number, integer, boolean, and array are allowed",
},
}
@ -1458,10 +1530,8 @@ func TestElicitContentValidation(t *testing.T) {
Type: "string",
OneOf: []*jsonschema.Schema{
{
Const: anyPtr(map[string]string{
"const": "high",
"title": "High Priority",
}),
Const: anyPtr("high"),
Title: "High Priority",
},
},
},
@ -1478,10 +1548,8 @@ func TestElicitContentValidation(t *testing.T) {
Type: "string",
OneOf: []*jsonschema.Schema{
{
Const: anyPtr(map[string]string{
"const": "potato",
"title": "Potato Priority",
}),
Const: anyPtr("potato"),
Title: "Potato Priority",
},
},
},