diff --git a/src/main/resources/swagger/ga4gh-tool-discovery.yaml b/src/main/resources/swagger/ga4gh-tool-discovery.yaml
index f749868e..119ed305 100644
--- a/src/main/resources/swagger/ga4gh-tool-discovery.yaml
+++ b/src/main/resources/swagger/ga4gh-tool-discovery.yaml
@@ -113,16 +113,29 @@ paths:
           schema:
             $ref: '#/definitions/Error'
 definitions:
-  
+  ToolType:
+    # thought. it would be nicer if ToolTypes are consistent across registries. How would we accomplish this? Operate a MIME-type like list? 
+    description: Describes a type of tool allowing us to categorize workflows, the language of the workflow, tools, and maybe even other entities separately
+    properties:
+      id:
+        type: string
+        description: The unique identifier for the type
+      name:
+        type: string
+        description: A short friendly name for the type
+      description:
+        type: string
+        description: A longer explanation of what this type is and what it can accomplish
   Tool:
-    description: A tool (or described tool) describes one pairing of a tool as described in a descriptor file (which potentially describes multiple tools) and a Docker image. 
-    required: 
-      - id 
+    description: A tool (or described tool) describes one pairing of a tool as described in a descriptor file (which potentially describes multiple tools) and a Docker image.
+    required:
+      - id
       - registry
-      - organization 
+      - organization
       - name
       - author
       - meta-version
+      - tooltype
     properties:
       id:
         type: string
@@ -139,6 +152,9 @@ definitions:
       toolname:
         type: string
         description: The name of the tool.
+      tooltype:
+        $ref: '#/definitions/ToolType'
+        description: A constrained category for the tool.
       description:
         type: string
         description: The description of the tool.
@@ -147,14 +163,14 @@ definitions:
         description: The author of the tool.
       meta-version:
         type: string
-        description: The version of this entry of the registry. Iterates when fields like the description, author, etc. are updated. 
+        description: 'The version of this entry of the registry. Iterates when fields like the description, author, etc. are updated.'
       versions:
         type: array
         items:
           $ref: '#/definitions/ToolVersion'
   ToolVersion:
-    description: A tool version describes a particular iteration of a tool as described by a reference to a specific image and dockerfile. 
-    required: 
+    description: A tool version describes a particular iteration of a tool as described by a reference to a specific image and dockerfile.
+    required:
       - id
       - descriptor
       - image
@@ -172,9 +188,9 @@ definitions:
         description: The docker path to the image (and version) for this tool. (e.g. quay.io/seqware/seqware_full/1.1)
       dockerfile:
         type: string
-        description: The url to the dockerfile used to build this image, should include version information (e.g. https://github.com/ICGC-TCGA-PanCancer/pcawg_delly_workflow/blob/master/delly_docker/Dockerfile ) 
+        description: 'The url to the dockerfile used to build this image, should include version information (e.g. https://github.com/ICGC-TCGA-PanCancer/pcawg_delly_workflow/blob/master/delly_docker/Dockerfile )'
   ToolDescriptor:
-    description: A tool descriptor is a metadata document that describes one or more tools. 
+    description: A tool descriptor is a metadata document that describes one or more tools.
     required:
       - descriptor
     properties:
@@ -183,7 +199,7 @@ definitions:
         description: The descriptor that represents this version of the tool. (CWL or WDL)
   ToolDockerfile:
     description: A tool dockerfile is a document that describes how to build a particular Docker image.
-    required: 
+    required:
       - dockerfile
     properties:
       dockerfile:
@@ -198,3 +214,4 @@ definitions:
       message:
         type: string
         default: Internal Server Error
+