feat: add schema tools

Add 2 mcp tools for querying schema versions and blame.
- get_schema_versions()
- get_schema_blame()

Author: eagle-25

README.md

@@ -11,6 +11,7 @@ Supports both DataHub Core and DataHub Cloud.
 - Fetching metadata for any entity
 - Traversing the lineage graph, both upstream and downstream
 - Listing SQL queries associated with a dataset
+- Querying schema versions and schema blame.
 
 ## Demo
 

src/mcp_server_datahub/gql/entity_details.gql

@@ -1205,3 +1205,45 @@ query GetEntityLineage($input: SearchAcrossLineageInput!) {
     }
   }
 }
+
+query getSchemaVersionList($input: GetSchemaVersionListInput!) {
+  getSchemaVersionList(input: $input) {
+    latestVersion {
+      semanticVersion
+      semanticVersionTimestamp
+      versionStamp
+      __typename
+    }
+    semanticVersionList {
+      semanticVersion
+      semanticVersionTimestamp
+      versionStamp
+      __typename
+    }
+    __typename
+  }
+}
+
+
+query getSchemaBlame($input: GetSchemaBlameInput!) {
+  getSchemaBlame(input: $input) {
+    version {
+      semanticVersion
+      semanticVersionTimestamp
+      versionStamp
+      __typename
+    }
+    schemaFieldBlameList {
+      fieldPath
+      schemaFieldChange {
+        timestampMillis
+        lastSemanticVersion
+        lastSchemaFieldChange
+        versionStamp
+        __typename
+      }
+      __typename
+    }
+    __typename
+  }
+}

src/mcp_server_datahub/mcp_server.py

@@ -313,6 +313,47 @@ def get_lineage(urn: str, upstream: bool, max_hops: int = 1) -> dict:
     return lineage
 
 
+@mcp.tool(description="Retrieve schema versions for a given dataset URN.")
+def get_schema_versions(dataset_urn: str) -> List[Dict[str, Any]]:
+    client = get_client()
+
+    variables = {
+        "input": {
+            "datasetUrn": dataset_urn,
+        }
+    }
+
+    response = _execute_graphql(
+        client._graph,
+        query=entity_details_fragment_gql,
+        variables=variables,
+        operation_name="getSchemaVersionList",
+    )
+
+    return response.get("getSchemaVersionList", [])
+
+
+@mcp.tool(description="Use this tool to get a schema blame.")
+def get_schema_blame(datasetUrn: str, version: str) -> Dict[str, Any]:
+    client = get_client()
+
+    variables = {
+        "input": {
+            "datasetUrn": datasetUrn,
+            "version": version,
+        }
+    }
+
+    resp = _execute_graphql(
+        client._graph,
+        query=entity_details_fragment_gql,
+        variables=variables,
+        operation_name="getSchemaBlame",
+    )
+
+    return resp.get("getSchemaBlame", {})
+
+
 if __name__ == "__main__":
     import sys
 
@@ -348,3 +389,9 @@ def _divider() -> None:
     _divider()
     print("Getting queries", urn)
     print(json.dumps(get_dataset_queries(urn), indent=2))
+    _divider()
+    print("Getting schema versions", urn)
+    print(json.dumps(get_schema_versions(urn), indent=2))
+    _divider()
+    print("Getting schema blame", urn)
+    print(json.dumps(get_schema_blame(urn, "latest"), indent=2))

tests/test_mcp_server.py

@@ -10,6 +10,8 @@
     get_dataset_queries,
     get_entity,
     get_lineage,
+    get_schema_blame,
+    get_schema_versions,
     search,
     with_client,
 )
@@ -58,6 +60,16 @@ def test_search() -> None:
     assert res is not None
 
 
+def test_get_schema_version() -> None:
+    res = get_schema_versions(_test_urn)
+    assert res is not None
+
+
+def test_get_schema_blame() -> None:
+    res = get_schema_blame(_test_urn)
+    assert res is not None
+
+
 if __name__ == "__main__":
     import pytest