Previous value: -"Feature types to retrieve. Default is gene only. Requesting variation in a large region can return tens of thousands of features. Include variation only for targeted small regions (single gene loci or smaller)."New value: +"Feature types to retrieve — at least one. Default is gene only. Requesting variation in a large region can match tens of thousands of features. Include variation only for targeted small regions (single gene loci or smaller)."

Added value: +1

Added value: +{
+  "default": 100,
+  "description": "Maximum number of features to return. A gene-length region can hold tens of thousands of variation features; the default keeps the response compact. Set to 0 to return every feature uncapped. totalCount always reports the true number found before this cap.",
+  "maximum": 9007199254740991,
+  "minimum": 0,
+  "type": "integer"
+}

Previous value: -"Genomic region in chr:start-end format (e.g. 13:32315086-32400268). Ensembl normalizes chromosome names and canonical vertebrate output omits the chr prefix (13, not chr13); a chr-prefixed name like chr13 is also accepted. For large regions (>100 kb), limit to gene feature type to avoid overwhelming results."New value: +"Genomic region in chr:start-end format (e.g. 13:32315086-32400268). Ensembl serves at most 5,000,000 bases per region; split a larger area into smaller windows. Ensembl normalizes chromosome names and canonical vertebrate output omits the chr prefix (13, not chr13); a chr-prefixed name like chr13 is also accepted. For large regions (>100 kb), limit to gene feature type to avoid overwhelming results."

Added value: +1

Added value: +1

Added value: +{
+  "description": "Genome assembly the coordinates are on (e.g. GRCh38). Omitted only when it could not be resolved, in which case the notice says so.",
+  "type": "string"
+}

Added value: +{
+  "description": "The max_results limit applied to the feature list.",
+  "type": "number"
+}

Previous value: -"Machine-readable failure mode. Declared by this tool: `invalid_region`: The region string could not be parsed or contains invalid coordinates. `invalid_species`: The species string was not recognized by Ensembl. Other values are possible when a failure originates below the handler."New value: +"Machine-readable failure mode. Declared by this tool: `invalid_region`: The region string could not be parsed, contains invalid coordinates, or spans more than the 5,000,000-base maximum. `invalid_species`: The species string was not recognized by Ensembl. Other values are possible when a failure originates below the handler."

Previous value: -"Genomic features found in the requested region."New value: +"Genomic features found in the requested region, capped to max_results. totalCount reports the full count found before the cap."

Previous value: -"Warning or guidance about the result set."New value: +"Guidance about the result set: empty, large, capped, or missing assembly."

Added value: +{
+  "description": "Number of features returned after the max_results cap.",
+  "type": "number"
+}

Previous value: -"Number of features returned. Note: very large regions may return truncated results."New value: +"Total number of features found in the region before the max_results cap. Exceeds the returned features count when the list was capped."

Added value: +{
+  "description": "True when the feature list was capped at max_results.",
+  "type": "boolean"
+}

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

Added value: +false

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

Added value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "features",
+      "totalCount",
+      "region",
+      "species"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]

Added value: +{
+  "additionalProperties": {},
+  "description": "Present when the call failed. Absent on success.",
+  "properties": {
+    "code": {
+      "description": "JSON-RPC error code for this failure.",
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    "data": {
+      "additionalProperties": {},
+      "properties": {
+        "reason": {
+          "description": "Machine-readable failure mode. Declared by this tool: `invalid_region`: The region string could not be parsed or contains invalid coordinates. `invalid_species`: The species string was not recognized by Ensembl. Other values are possible when a failure originates below the handler.",
+          "examples": [
+            "invalid_region",
+            "invalid_species"
+          ],
+          "type": "string"
+        },
+        "recovery": {
+          "additionalProperties": {},
+          "description": "Actionable next step for the caller.",
+          "properties": {
+            "hint": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "hint"
+          ],
+          "type": "object"
+        },
+        "retryable": {
+          "description": "Whether retrying may succeed.",
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable description of what went wrong.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "code",
+    "message"
+  ],
+  "type": "object"
+}

Removed value: -[
-  "features",
-  "totalCount",
-  "region",
-  "species"
-]

Previous value: -"Genomic region in chr:start-end format (e.g. 13:32315086-32400268). Chromosome names use Ensembl format — no \"chr\" prefix for vertebrates (13, not chr13). For large regions (>100 kb), limit to gene feature type to avoid overwhelming results."New value: +"Genomic region in chr:start-end format (e.g. 13:32315086-32400268). Ensembl normalizes chromosome names and canonical vertebrate output omits the chr prefix (13, not chr13); a chr-prefixed name like chr13 is also accepted. For large regions (>100 kb), limit to gene feature type to avoid overwhelming results."

Added value: +{
+  "description": "Parent transcript ID (ENST…) for exon features. An exon is reported once per parent transcript it belongs to, so the same exon ID can appear on multiple rows that differ only by this field — not duplicates.",
+  "type": "string"
+}

Added value: +{
+  "description": "Position (1-based) of an exon within its parent transcript.",
+  "type": "number"
+}