Previous value: -"Optional biotype filter (e.g. protein_coding, lncRNA, SNV). Applied server-side by Ensembl. Not all feature types support biotype filtering."New value: +"Optional biotype filter (e.g. protein_coding, lncRNA, SNV). Case-sensitive (lncRNA, not lncrna); remove the filter to inspect all matching feature types. Applied server-side by Ensembl. Not all feature types support biotype filtering."

Previous 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."New value: +"Genomic region as chr:start-end with species set (e.g. 13:32315086-32400268), or species:chr:start-end (e.g. homo_sapiens:13:32315086-32400268), with start at or below end. 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. The mitochondrion is MT in vertebrates, mitochondrion_genome in Drosophila, and MtDNA in C. elegans; M and chrM are accepted only where Ensembl resolves them to the mitochondrion (Drosophila, for one) and otherwise fail as invalid_region naming the mitochondrion of the species. For large regions (>100 kb), limit to gene feature type to avoid overwhelming results."

Previous value: -"Species in Ensembl internal format (e.g. homo_sapiens, mus_musculus). Use ensembl_list_species to discover valid values."New value: +"Species in Ensembl internal format (e.g. homo_sapiens, mus_musculus). Required for a bare chr:start-end region; for the species:chr:start-end form the species in region takes precedence and this field is ignored. Use ensembl_list_species with nameContains (a genus or common name, e.g. mouse) to find valid values."

Previous value: -[
-  "species",
-  "region"
-]New value: +[
+  "region"
+]

Previous 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."New value: +"Machine-readable failure mode. Declared by this tool: `invalid_region`: The region string could not be parsed, has its start greater than its end, names the mitochondrion M or chrM where Ensembl resolves that to another region or none, contains coordinates outside the sequence region, or spans more than the 5,000,000-base maximum. `invalid_species`: The species (the species field or the region's species prefix) was not recognized by Ensembl. `missing_species`: A bare chr:start-end region was given without a species. Other values are possible when a failure originates below the handler."

Previous value: -[
-  "invalid_region",
-  "invalid_species"
-]New value: +[
+  "invalid_region",
+  "invalid_species",
+  "missing_species"
+]

Previous value: -"The region queried, as provided."New value: +"The region queried, as provided minus any species prefix (reported as species)."

Previous value: -"The species queried."New value: +"The species queried: the region's species prefix when it has one, otherwise the species field."

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"
+}