diff --git a/packages/physics/src/traits/emitter.js b/packages/physics/src/traits/emitter.js
index 484f833..4a3bfc5 100644
--- a/packages/physics/src/traits/emitter.js
+++ b/packages/physics/src/traits/emitter.js
@@ -37,57 +37,51 @@ export default (latus) => class Emitter extends decorate(Trait) {
     this.#emitter.addEventListener('PARTICLE_UPDATE', this.#onParticleUpdate);
   }
 
-  static behaviorTypes() {
-    return {
-      emitParticleEntity: {
-        cycle: true,
-        type: 'entity',
-        label: 'Create particle.',
-        args: [
-          ['entity', {
-            type: 'entity',
-          }],
-        ],
-      },
-      emitParticleJson: {
-        type: 'stream',
-        label: 'Create particle.',
-        args: [
-          ['json', {
-            type: 'object',
-          }],
-        ],
-      },
-      emitParticle: {
-        type: 'stream',
-        label: 'Create particle.',
-        args: [
-          ['key', {
-            type: 'string',
-            options: (entity) => (
-              Object.keys(entity.trait('Emitter').particles)
-                .reduce((r, key) => ({...r, [key]: key}), {})
-            ),
-          }],
-          ['json', {
-            type: 'object',
-          }],
-        ],
-      },
-    };
-  }
-
   static defaultParams() {
     return {
       particles: {},
     };
   }
 
-  static describeParams() {
+  static describe(entity) {
     return {
-      particles: {
-        type: 'object',
-        label: 'Particles',
+      emitParticleEntity: {
+        type: 'entity',
+        label: 'Create particle.',
+        args: [
+          {
+            label: 'entity',
+            type: 'entity',
+          },
+        ],
+      },
+      emitParticleJson: {
+        type: 'void',
+        label: 'Create particle.',
+        args: [
+          {
+            label: 'json',
+            type: 'object',
+          },
+        ],
+      },
+      emitParticle: {
+        type: 'void',
+        label: 'Create particle.',
+        args: [
+          {
+            label: 'key',
+            type: 'string',
+            options: () => (
+              Object.keys(entity.trait('Emitter').particles)
+                .reduce((r, key) => ({...r, [key]: key}), {})
+            ),
+          },
+          {
+            label: 'json',
+            type: 'object',
+          },
+        ],
       },
     };
   }