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fix(mcp): fold non-string enums into descriptions for tools/list #39

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Merged
KristofersOzolinsMagebit merged 1 commit into from
Aug 19, 2026
Merged

fix(mcp): fold non-string enums into descriptions for tools/list #39

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2 changes: 1 addition & 1 deletion Model/JsonRpc/Handler/ToolsListHandler.php
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Original file line number Diff line number Diff line change
Expand Up @@ -88,7 +88,7 @@ public function handle(Request $request, AuthenticatedContext $context): Respons
'name' => str_replace('.', '_', $tool->getName()),
'title' => $displayTitle,
'description' => $tool->getDescription(),
'inputSchema' => $this->schemaSanitizer->sanitize(
'inputSchema' => $this->schemaSanitizer->sanitizeForClient(
$tool->getName(),
$tool->getInputSchema()
),
Expand Down
64 changes: 61 additions & 3 deletions Model/Tool/SchemaSanitizer.php
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Original file line number Diff line number Diff line change
Expand Up @@ -38,17 +38,33 @@ public function __construct(
public function sanitize(string $toolName, array $schema): array
{
/** @var array<string, mixed> $walked */
$walked = $this->walk($toolName, $schema, '');
$walked = $this->walk($toolName, $schema, '', false);
return $walked;
}

/**
* Same as {@see sanitize()} plus the rewrites clients need. Only for what
* `tools/list` advertises — argument validation keeps the stricter schema.
*
* @param string $toolName
* @param array<string, mixed> $schema
* @return array<string, mixed>
*/
public function sanitizeForClient(string $toolName, array $schema): array
{
/** @var array<string, mixed> $walked */
$walked = $this->walk($toolName, $schema, '', true);
return $walked;
}

/**
* @param string $toolName
* @param mixed $node
* @param string $path
* @param bool $forClient
* @return mixed
*/
private function walk(string $toolName, mixed $node, string $path): mixed
private function walk(string $toolName, mixed $node, string $path, bool $forClient): mixed
{
if (!is_array($node)) {
return $node;
Expand All @@ -68,15 +84,57 @@ private function walk(string $toolName, mixed $node, string $path): mixed
}
}

if ($forClient) {
$node = $this->foldNonStringEnum($node);
}

$cleaned = [];
foreach ($node as $key => $value) {
$childPath = $path === '' ? (string) $key : $path . '.' . $key;
if ($key === 'properties' && is_array($value) && $value === []) {
$cleaned[$key] = new stdClass();
continue;
}
$cleaned[$key] = $this->walk($toolName, $value, $childPath);
$cleaned[$key] = $this->walk($toolName, $value, $childPath, $forClient);
}
return $cleaned;
}

/**
* Replaces an `enum` holding non-string values with a description of them.
*
* @param array<mixed> $node
* @return array<mixed>
*/
private function foldNonStringEnum(array $node): array
{
$values = $node['enum'] ?? null;
if (!is_array($values) || !array_is_list($values) || $values === []) {
return $node;
}
foreach ($values as $value) {
if (!is_string($value)) {
unset($node['enum']);
$node['description'] = $this->describeValues($node['description'] ?? null, $values);
return $node;
}
}
return $node;
}

/**
* @param mixed $description
* @param array<int, mixed> $values
* @return string
*/
private function describeValues(mixed $description, array $values): string
{
$encoded = array_map(
static fn (mixed $value): string => (string) json_encode($value, JSON_UNESCAPED_SLASHES),
$values
);
$sentence = sprintf('Allowed values: %s.', implode(', ', $encoded));
$existing = is_string($description) ? trim($description) : '';
return $existing === '' ? $sentence : $existing . ' ' . $sentence;
}
}
173 changes: 173 additions & 0 deletions Test/Unit/Model/Tool/SchemaSanitizerTest.php
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Original file line number Diff line number Diff line change
Expand Up @@ -174,4 +174,177 @@ public function testEmptyPropertiesNormalizedAtNestedDepth(): void
self::assertIsArray($address);
self::assertInstanceOf(\stdClass::class, $address['properties']);
}

public function testDropsIntegerEnumAndFoldsValuesIntoDescription(): void
{
$schema = [
'type' => 'object',
'properties' => [
'status' => [
'type' => 'integer',
'enum' => [1, 2],
'description' => 'Product status.',
],
],
'required' => ['status'],
];

$expected = [
'type' => 'object',
'properties' => [
'status' => [
'type' => 'integer',
'description' => 'Product status. Allowed values: 1, 2.',
],
],
'required' => ['status'],
];

self::assertSame($expected, $this->sanitizer->sanitizeForClient('test.tool', $schema));
}

public function testValidationSchemaKeepsIntegerEnum(): void
{
$schema = [
'type' => 'object',
'properties' => [
'status' => ['type' => 'integer', 'enum' => [1, 2]],
],
];

self::assertSame($schema, $this->sanitizer->sanitize('test.tool', $schema));
}

public function testDroppedEnumWithoutDescriptionGetsOne(): void
{
$schema = [
'type' => 'object',
'properties' => [
'visibility' => ['type' => 'integer', 'enum' => [1, 2, 3, 4]],
],
];

$expected = [
'type' => 'object',
'properties' => [
'visibility' => [
'type' => 'integer',
'description' => 'Allowed values: 1, 2, 3, 4.',
],
],
];

self::assertSame($expected, $this->sanitizer->sanitizeForClient('test.tool', $schema));
}

public function testKeepsStringEnumUntouched(): void
{
$schema = [
'type' => 'object',
'properties' => [
'sort_dir' => [
'type' => 'string',
'enum' => ['asc', 'desc'],
'description' => 'Sort direction.',
],
],
];

self::assertSame($schema, $this->sanitizer->sanitizeForClient('test.tool', $schema));
}

public function testDropsEnumNestedInsideArrayItems(): void
{
$schema = [
'type' => 'object',
'properties' => [
'items' => [
'type' => 'array',
'items' => [
'type' => 'object',
'properties' => [
'sku' => ['type' => 'string'],
'backorders' => [
'type' => 'integer',
'enum' => [0, 1, 2],
'description' => '0 = no, 1 = allow.',
],
],
'required' => ['sku'],
],
],
],
'required' => ['items'],
];

$expected = [
'type' => 'object',
'properties' => [
'items' => [
'type' => 'array',
'items' => [
'type' => 'object',
'properties' => [
'sku' => ['type' => 'string'],
'backorders' => [
'type' => 'integer',
'description' => '0 = no, 1 = allow. Allowed values: 0, 1, 2.',
],
],
'required' => ['sku'],
],
],
],
'required' => ['items'],
];

self::assertSame($expected, $this->sanitizer->sanitizeForClient('test.tool', $schema));
}

public function testDropsEnumMixingStringsAndNumbers(): void
{
$schema = [
'type' => 'object',
'properties' => [
'mode' => ['type' => 'string', 'enum' => ['all', 0]],
],
];

$expected = [
'type' => 'object',
'properties' => [
'mode' => [
'type' => 'string',
'description' => 'Allowed values: "all", 0.',
],
],
];

self::assertSame($expected, $this->sanitizer->sanitizeForClient('test.tool', $schema));
}

public function testLeavesPropertyNamedEnumAlone(): void
{
$schema = [
'type' => 'object',
'properties' => [
'enum' => ['type' => 'string', 'description' => 'A field named enum.'],
],
'required' => ['enum'],
];

self::assertSame($schema, $this->sanitizer->sanitizeForClient('test.tool', $schema));
}

public function testLeavesPropertyNamedEnumWithNumericKeywordsAlone(): void
{
$schema = [
'type' => 'object',
'properties' => [
'enum' => ['type' => 'integer', 'minimum' => 1],
],
];

self::assertSame($schema, $this->sanitizer->sanitizeForClient('test.tool', $schema));
}
}
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