ec2 plugin 1.17 also has support for setting tags on instances, but that doesn't seem to work:

Launching ami-4bee4422 Looking for existing instances: {Filters: [{Name: image-id, Values: [ami-4bee4422], }, {Name: availability-zone, Values: [us-east-1b], }, {Name: key-name, Values: [jenkins-slave], }, {Name: instance-type, Values: [m1.xlarge], }, {Name: tag:Name, Values: [test], }, {Name: instance-state-name, Values: [stopped, stopping], }], } ERROR: You must specify one or more tags to create ha:AAAAWB+LCAAAAAAAAABb85aBtbiIQSmjNKU4P08vOT+vOD8nVc8DzHWtSE4tKMnMz/PLL0ldFVf2c+b/lb5MDAwVRQxSaBqcITRIIQMEMIIUFgAAckCEiWAAAAA=Status Code: 400, AWS Service: AmazonEC2, AWS Request ID: f17f58ad-2515-4b71-a5e7-de86531be347, AWS Error Code: InvalidParameterValue, AWS Error Message: You must specify one or more tags to create at com.amazonaws.http.AmazonHttpClient.handleErrorResponse(AmazonHttpClient.java:547) at com.amazonaws.http.AmazonHttpClient.executeHelper(AmazonHttpClient.java:284) at com.amazonaws.http.AmazonHttpClient.execute(AmazonHttpClient.java:169) at com.amazonaws.services.ec2.AmazonEC2Client.invoke(AmazonEC2Client.java:5684) at com.amazonaws.services.ec2.AmazonEC2Client.createTags(AmazonEC2Client.java:3102) at hudson.plugins.ec2.SlaveTemplate.provision(SlaveTemplate.java:292) at hudson.plugins.ec2.EC2Cloud.doProvision(EC2Cloud.java:207) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:616) at org.kohsuke.stapler.Function$InstanceFunction.invoke(Function.java:288) at org.kohsuke.stapler.Function.bindAndInvoke(Function.java:151) at org.kohsuke.stapler.Function.bindAndInvokeAndServeResponse(Function.java:90) at org.kohsuke.stapler.MetaClass$1.doDispatch(MetaClass.java:111) at org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:53) at org.kohsuke.stapler.Stapler.tryInvoke(Stapler.java:563) at org.kohsuke.stapler.Stapler.invoke(Stapler.java:648) at org.kohsuke.stapler.MetaClass$6.doDispatch(MetaClass.java:241) at org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:53) at org.kohsuke.stapler.Stapler.tryInvoke(Stapler.java:563) at org.kohsuke.stapler.Stapler.invoke(Stapler.java:648) at org.kohsuke.stapler.Stapler.invoke(Stapler.java:477) at org.kohsuke.stapler.Stapler.service(Stapler.java:159) at javax.servlet.http.HttpServlet.service(HttpServlet.java:45) at winstone.ServletConfiguration.execute(ServletConfiguration.java:248) at winstone.RequestDispatcher.forward(RequestDispatcher.java:333) at winstone.RequestDispatcher.doFilter(RequestDispatcher.java:376) at hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:95) at hudson.util.PluginServletFilter.doFilter(PluginServletFilter.java:87) at winstone.FilterConfiguration.execute(FilterConfiguration.java:194) at winstone.RequestDispatcher.doFilter(RequestDispatcher.java:366) at hudson.security.csrf.CrumbFilter.doFilter(CrumbFilter.java:47) at winstone.FilterConfiguration.execute(FilterConfiguration.java:194) at winstone.RequestDispatcher.doFilter(RequestDispatcher.java:366) at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:84) at hudson.security.UnwrapSecurityExceptionFilter.doFilter(UnwrapSecurityExceptionFilter.java:51) at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87) at org.acegisecurity.ui.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:166) at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87) at org.acegisecurity.providers.anonymous.AnonymousProcessingFilter.doFilter(AnonymousProcessingFilter.java:125) at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87) at org.acegisecurity.ui.rememberme.RememberMeProcessingFilter.doFilter(RememberMeProcessingFilter.java:142) at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87) at org.acegisecurity.ui.AbstractProcessingFilter.doFilter(AbstractProcessingFilter.java:271) at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87) at org.acegisecurity.ui.basicauth.BasicProcessingFilter.doFilter(BasicProcessingFilter.java:173) at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87) at jenkins.security.ApiTokenFilter.doFilter(ApiTokenFilter.java:61) at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87) at org.acegisecurity.context.HttpSessionContextIntegrationFilter.doFilter(HttpSessionContextIntegrationFilter.java:249) at hudson.security.HttpSessionContextIntegrationFilter2.doFilter(HttpSessionContextIntegrationFilter2.java:66) at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87) at hudson.security.ChainedServletFilter.doFilter(ChainedServletFilter.java:76) at hudson.security.HudsonFilter.doFilter(HudsonFilter.java:164) at winstone.FilterConfiguration.execute(FilterConfiguration.java:194) at winstone.RequestDispatcher.doFilter(RequestDispatcher.java:366) at hudson.util.CharacterEncodingFilter.doFilter(CharacterEncodingFilter.java:81) at winstone.FilterConfiguration.execute(FilterConfiguration.java:194) at winstone.RequestDispatcher.doFilter(RequestDispatcher.java:366) at winstone.RequestDispatcher.forward(RequestDispatcher.java:331) at winstone.RequestHandlerThread.processRequest(RequestHandlerThread.java:245) at winstone.RequestHandlerThread.run(RequestHandlerThread.java:148) at java.lang.Thread.run(Thread.java:636)