Autonomous, reactive and proactive features of software agents make development of agent-based software systems complex. A Domain-specific Language (DSL) can provide the required abstraction and hence support a more fruitful methodology for the development of Multi-agent Systems (MASs) especially working on the new challenging environments such as the Semantic Web. Based on our previously introduced domain-specific metamodel, in this paper we propose a textual concrete syntax of a DSL for MASs working on the Semantic Web and show how the specifications of this DSL can be utilized during the code generation of exact MASs. The new DSL is called Semantic web Enabled Agent Language (SEA_L). The syntax of SEA_L is supported with textual modeling toolkits developed with Xtext. The practical use of SEA_L is illustrated with a case study which considers the modeling of a multi-agent based e-barter system.