Previous value: -"RFC 5322 From header. The sender domain must be a verified outbound domain for your organization."New value: +"RFC 5322 From header: YOUR OWN complete mailbox address, never the recipient's. createEmailAddress.address and getAccount.managed_inbox_address are domains, not mailbox addresses. When present, use the sender_address added to those MCP results, such as agent@pink-ram.primitive.email. Putting the recipient's address here mails them as themselves, which they will ignore. The sender domain must be a verified outbound domain for your organization."

Added value: +{
+  "description": "Primitive API key (prim_...). Only needed when this connection has no signed-in account: pass the api_key returned by createEmailAddress, unchanged, on every call for the rest of the conversation. Omit it when the user is signed in.",
+  "maxLength": 200,
+  "minLength": 8,
+  "type": "string"
+}

Previous value: -"Optional file attachments."New value: +"Optional file attachments. Not allowed on scheduled sends (scheduled_at)."

Added value: +{
+  "description": "Content-ID for an inline (cid) attachment: 1-128 printable ASCII characters, no whitespace or angle brackets. When set, the part renders inline and body_html can reference it (e.g. src=\"cid:logo-1\"). Omit for a regular downloadable attachment.",
+  "maxLength": 128,
+  "minLength": 1,
+  "pattern": "^[\\x21-\\x3B\\x3D\\x3F-\\x7E]+$",
+  "type": "string"
+}

Previous value: -"MIME type of the attachment (e.g. \"application/pdf\")."New value: +"MIME type of the attachment (e.g. \"application/pdf\"). Inferred from the filename when omitted."

Added value: +{
+  "description": "Optional BCC recipients: a single address or an array of single-address strings (each entry exactly one address). Counts toward the combined to+cc+bcc max of 100.",
+  "oneOf": [
+    {
+      "maxLength": 998,
+      "minLength": 3,
+      "type": "string"
+    },
+    {
+      "items": {
+        "maxLength": 998,
+        "minLength": 3,
+        "type": "string"
+      },
+      "maxItems": 100,
+      "minItems": 1,
+      "type": "array"
+    }
+  ]
+}

Previous value: -"HTML message body. Provide at least one of body_text or body_html."New value: +"HTML message body. Provide at least one of body_text or body_html. Reference inline attachments via cid: URLs matching their content_id."

Added value: +{
+  "description": "Optional CC recipients: a single address or an array of single-address strings (each entry exactly one address). Counts toward the combined to+cc+bcc max of 100.",
+  "oneOf": [
+    {
+      "maxLength": 998,
+      "minLength": 3,
+      "type": "string"
+    },
+    {
+      "items": {
+        "maxLength": 998,
+        "minLength": 3,
+        "type": "string"
+      },
+      "maxItems": 100,
+      "minItems": 1,
+      "type": "array"
+    }
+  ]
+}

Added value: +{
+  "description": "Optional Reply-To header: a single address or an array of up to 10 single-address entries. A pure header: adds no recipients and does not count toward the recipient cap.",
+  "oneOf": [
+    {
+      "maxLength": 998,
+      "minLength": 3,
+      "type": "string"
+    },
+    {
+      "items": {
+        "maxLength": 998,
+        "minLength": 3,
+        "type": "string"
+      },
+      "maxItems": 10,
+      "minItems": 1,
+      "type": "array"
+    }
+  ]
+}

Added value: +{
+  "description": "Schedule the send for a future time (ISO 8601 UTC, e.g. \"2026-08-01T09:00:00Z\"). Must be strictly in the future and at most 30 days out. Cannot be combined with wait or with attachments. Cancel before dispatch with cancelScheduledSend.",
+  "format": "date-time",
+  "type": "string"
+}

Added value: +{
+  "description": "Optional metadata tags (max 10, unique names) stored on the send record for correlation and filtering via listSentEmails. Never rendered into headers and never delivered.",
+  "items": {
+    "additionalProperties": false,
+    "properties": {
+      "name": {
+        "description": "Tag name: ASCII letters, digits, underscores, dashes only.",
+        "maxLength": 64,
+        "minLength": 1,
+        "pattern": "^[A-Za-z0-9_-]+$",
+        "type": "string"
+      },
+      "value": {
+        "description": "Tag value: same charset as the name. Use \"true\" for a bare marker tag.",
+        "maxLength": 256,
+        "minLength": 1,
+        "pattern": "^[A-Za-z0-9_-]+$",
+        "type": "string"
+      }
+    },
+    "required": [
+      "name",
+      "value"
+    ],
+    "type": "object"
+  },
+  "maxItems": 10,
+  "type": "array"
+}

Previous value: -"Recipient email address (RFC 5321 mailbox)."New value: +"Recipient email address (RFC 5321 mailbox, display-name form allowed), or an array of single-address strings to address multiple recipients with one message. Each array entry must be exactly one address. Combined to+cc+bcc count max 100."

Removed value: -320

Removed value: -3

Added value: +[
+  {
+    "maxLength": 998,
+    "minLength": 3,
+    "type": "string"
+  },
+  {
+    "items": {
+      "maxLength": 998,
+      "minLength": 3,
+      "type": "string"
+    },
+    "maxItems": 100,
+    "minItems": 1,
+    "type": "array"
+  }
+]

Removed value: -"string"

Previous value: -"When true, wait for the first SMTP delivery outcome before returning. Respects wait_timeout_ms."New value: +"When true, wait for the first SMTP delivery outcome before returning. Respects wait_timeout_ms. Cannot be combined with scheduled_at."

Previous value: -"How long to wait for delivery confirmation when wait is true (1000–30000 ms, default 10000)."New value: +"How long to wait for delivery confirmation when wait is true (1000-30000 ms, default 10000)."

Added value: +"Client-supplied idempotency key. Retrying with the same key returns the original result without re-sending."

Added value: +"Optional file attachments."

Added value: +"Base64-encoded attachment content."

Added value: +"MIME type of the attachment (e.g. \"application/pdf\")."

Added value: +"Attachment filename including extension."

Added value: +"HTML message body. Provide at least one of body_text or body_html."

Added value: +"Plain-text message body. Provide at least one of body_text or body_html."

Added value: +"Message-ID of the email being replied to, for threading (e.g. \"<abc@example.com>\")."

Added value: +"List of Message-IDs for the References header, oldest-first."

Added value: +"Email subject line."

Added value: +"Recipient email address (RFC 5321 mailbox)."

Added value: +"When true, wait for the first SMTP delivery outcome before returning. Respects wait_timeout_ms."

Added value: +"How long to wait for delivery confirmation when wait is true (1000–30000 ms, default 10000)."