Waaseyaa:mcp Endpoint

MCP Endpoint Specialist

Scope

This skill covers the MCP (Model Context Protocol) package:

• packages/mcp/src/ -- McpEndpoint, McpResponse, McpRouteProvider, McpServerCard
• packages/mcp/src/Auth/ -- McpAuthInterface, BearerTokenAuth
• packages/mcp/src/Bridge/ -- ToolRegistryInterface, ToolExecutorInterface

Use this skill when:

• Adding or modifying the MCP HTTP endpoint
• Working with JSON-RPC protocol handling
• Changing MCP authentication
• Adding new JSON-RPC methods or tool capabilities
• Wiring MCP routes into the front controller
• Working with the tool registry or executor bridge

Key Interfaces

McpEndpoint (packages/mcp/src/McpEndpoint.php)

final readonly class McpEndpoint
{
    public function __construct(
        private McpAuthInterface $auth,
        private ToolRegistryInterface $registry,
        private ToolExecutorInterface $executor,
    ) {}

    public function handle(
        string $method,
        string $body,
        ?string $authorizationHeader,
    ): McpResponse;
}

Single entry point for all MCP traffic. Authenticates, parses JSON-RPC, dispatches to internal handlers.

McpResponse (packages/mcp/src/McpResponse.php)

final readonly class McpResponse
{
    public function __construct(
        public string $body,
        public int $statusCode = 200,
        public string $contentType = 'application/json',
    ) {}
}

McpAuthInterface (packages/mcp/src/Auth/McpAuthInterface.php)

interface McpAuthInterface
{
    public function authenticate(?string $authorizationHeader): ?AccountInterface;
}

Returns AccountInterface on success, null on failure. BearerTokenAuth is the MVP implementation mapping opaque tokens to accounts.

ToolRegistryInterface (packages/mcp/src/Bridge/ToolRegistryInterface.php)

interface ToolRegistryInterface
{
    /** @return McpToolDefinition[] */
    public function getTools(): array;
    public function getTool(string $name): ?McpToolDefinition;
}

ToolExecutorInterface (packages/mcp/src/Bridge/ToolExecutorInterface.php)

interface ToolExecutorInterface
{
    public function execute(string $toolName, array $arguments): array;
}

Returns MCP tool result format: {content: [{type: "text", text: "..."}], isError?: bool}.

Architecture

JSON-RPC Dispatch Flow

POST /mcp
  -> McpEndpoint::handle()
    -> authenticate($authorizationHeader) -> AccountInterface | null (401)
    -> json_decode($body) -> parse error (-32700) | invalid request (-32600)
    -> match $request['method']:
        'initialize' -> protocol version, capabilities, server info
        'ping'       -> empty result
        'tools/list' -> ToolRegistryInterface::getTools() -> toArray()
        'tools/call' -> ToolExecutorInterface::execute($name, $arguments)
        default      -> method not found (-32601)

JSON-RPC Error Codes

Routes

McpRouteProvider registers two routes:

Note: Routes are defined in McpRouteProvider but not yet wired into public/index.php. This is a known gap.

Package Dependencies

• Layer 6 (Interfaces) -- can import from layers 0-5
• Depends on: waaseyaa/ai-schema (McpToolDefinition), waaseyaa/ai-agent (AgentExecutor), waaseyaa/routing, waaseyaa/access (AccountInterface)

Common Mistakes

JSON symmetry

Always pair json_encode(..., JSON_THROW_ON_ERROR) with json_decode(..., JSON_THROW_ON_ERROR). The endpoint already does this correctly -- maintain it.

AccountInterface, not concrete User

The auth interface returns ?AccountInterface (from waaseyaa/access), not a concrete User class (from waaseyaa/user). The MCP package must not depend on waaseyaa/user.

Tool result format

Tool executor must return {content: [{type: "text", text: "..."}]}. The isError key is optional (defaults to false). Don't return raw strings or arrays -- wrap in the content block format.

php://input is single-read

HttpRequest::createFromGlobals() consumes php://input. The front controller must pass the body via $httpRequest->getContent(), not re-read php://input.

Final classes cannot be mocked

All concrete classes are final readonly class. Use real instances in tests:

// Auth: use BearerTokenAuth with known tokens
$auth = new BearerTokenAuth(['test-token' => $account]);

// Registry/Executor: use anonymous classes implementing the interfaces
$registry = new class implements ToolRegistryInterface { ... };
$executor = new class implements ToolExecutorInterface { ... };

$endpoint = new McpEndpoint($auth, $registry, $executor);
$response = $endpoint->handle('POST', $body, 'Bearer test-token');

Testing Patterns

Unit Testing McpEndpoint

$auth = new BearerTokenAuth(['tok' => $account]);
$registry = new class implements ToolRegistryInterface {
    public function getTools(): array { return []; }
    public function getTool(string $name): ?McpToolDefinition { return null; }
};
$executor = new class implements ToolExecutorInterface {
    public function execute(string $toolName, array $arguments): array {
        return ['content' => [['type' => 'text', 'text' => 'ok']]];
    }
};

$endpoint = new McpEndpoint($auth, $registry, $executor);

// Test auth failure
$response = $endpoint->handle('POST', '{}', null);
assert($response->statusCode === 401);

// Test ping
$body = json_encode(['jsonrpc' => '2.0', 'method' => 'ping', 'id' => 1]);
$response = $endpoint->handle('POST', $body, 'Bearer tok');
assert($response->statusCode === 200);

Testing BearerTokenAuth

$auth = new BearerTokenAuth(['secret' => $account]);

assert($auth->authenticate(null) === null);
assert($auth->authenticate('Bearer wrong') === null);
assert($auth->authenticate('Bearer secret') === $account);
assert($auth->authenticate('bearer secret') === $account); // case-insensitive

Testing McpServerCard

$card = new McpServerCard(name: 'Test', version: '1.0.0', endpoint: '/mcp');
$json = $card->toJson();
$decoded = json_decode($json, true);
assert($decoded['endpoint'] === '/mcp');
assert($decoded['transport'] === 'streamable-http');

Related Specs

• docs/specs/mcp-endpoint.md -- Full MCP endpoint specification
• docs/specs/ai-integration.md -- AI layer that provides McpToolDefinition and AgentExecutor
• CLAUDE.md -- Project-wide gotchas including JSON symmetry and AccountInterface vs User