callTool method

Future<Object?> callTool({ required McpConnectionParams connectionParams, required String toolName, required Map<String, dynamic> args, Map<String, String>? headers, })

Calls one MCP tool and returns its JSON-like result payload.

Implementation

Future<Object?> callTool({
  required McpConnectionParams connectionParams,
  required String toolName,
  required Map<String, dynamic> args,
  Map<String, String>? headers,
}) async {
  final String key = _connectionKey(connectionParams);
  final McpToolExecutor? executor = _executorsByUrl[key]?[toolName];
  if (executor != null) {
    final Object? result = executor(args, headers: headers);
    if (result is Future<Object?>) {
      return result;
    }
    if (result is Future) {
      return await result;
    }
    return result;
  }

  if (connectionParams is StreamableHTTPConnectionParams &&
      !_remoteClient.isRemoteCapable(connectionParams)) {
    throw ArgumentError('MCP tool `$toolName` is not registered.');
  }

  await _ensureInitialized(connectionParams, headers: headers);
  if (!_hasCapability(connectionParams, 'tools')) {
    throw StateError(
      'MCP server `${_connectionLabel(connectionParams)}` does not expose `tools` capability.',
    );
  }

  final Object? result = await _call(
    connectionParams: connectionParams,
    method: 'tools/call',
    params: <String, Object?>{'name': toolName, 'arguments': args},
    headers: headers,
  );

  if (result is Map) {
    return _asStringObjectMap(result);
  }
  return result;
}