Sintassi errata vicino a "LIMIT" utilizzando mssql

Devi usare la clausola TOP invece di LIMIT

SELECT TOP 10 AgentScores.agentID, AgentScores.totalScore, Agents.firstname, Agents.lastname FROM AgentScores INNER JOIN Agents ON AgentScores.AgentId=Agents.Agent_id ORDER BY AgentScores.totalScore DESC