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taylorwilsdon

Google Workspace MCP Server - Control Gmail, Calendar, Docs, Sheets, Slides, Chat, Forms & Drive

get_gmail_messages_content_batch

Retrieve multiple Gmail message contents in one batch request. Supports up to 100 messages, with options for full body or metadata-only formats, streamlining email data extraction.

Instructions

Retrieves the content of multiple Gmail messages in a single batch request.
Supports up to 100 messages per request using Google's batch API.

Args:
    message_ids (List[str]): List of Gmail message IDs to retrieve (max 100).
    user_google_email (str): The user's Google email address. Required.
    format (Literal["full", "metadata"]): Message format. "full" includes body, "metadata" only headers.

Returns:
    str: A formatted list of message contents with separators.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
formatNofull
message_idsYes
serviceYes
user_google_emailYes

Implementation Reference

  • Main handler function implementing get_gmail_messages_content_batch tool. Uses Gmail API batch requests with fallback to sequential fetches for robustness against SSL errors. Extracts headers, bodies (text/HTML), and generates web links.
    @server.tool()
    @handle_http_errors("get_gmail_messages_content_batch", is_read_only=True, service_type="gmail")
    @require_google_service("gmail", "gmail_read")
    async def get_gmail_messages_content_batch(
        service,
        message_ids: List[str],
        user_google_email: str,
        format: Literal["full", "metadata"] = "full",
    ) -> str:
        """
        Retrieves the content of multiple Gmail messages in a single batch request.
        Supports up to 25 messages per batch to prevent SSL connection exhaustion.
    
        Args:
            message_ids (List[str]): List of Gmail message IDs to retrieve (max 25 per batch).
            user_google_email (str): The user's Google email address. Required.
            format (Literal["full", "metadata"]): Message format. "full" includes body, "metadata" only headers.
    
        Returns:
            str: A formatted list of message contents including subject, sender, recipients (To, Cc), and body (if full format).
        """
        logger.info(
            f"[get_gmail_messages_content_batch] Invoked. Message count: {len(message_ids)}, Email: '{user_google_email}'"
        )
    
        if not message_ids:
            raise Exception("No message IDs provided")
    
        output_messages = []
    
        # Process in smaller chunks to prevent SSL connection exhaustion
        for chunk_start in range(0, len(message_ids), GMAIL_BATCH_SIZE):
            chunk_ids = message_ids[chunk_start : chunk_start + GMAIL_BATCH_SIZE]
            results: Dict[str, Dict] = {}
    
            def _batch_callback(request_id, response, exception):
                """Callback for batch requests"""
                results[request_id] = {"data": response, "error": exception}
    
            # Try to use batch API
            try:
                batch = service.new_batch_http_request(callback=_batch_callback)
    
                for mid in chunk_ids:
                    if format == "metadata":
                        req = (
                            service.users()
                            .messages()
                            .get(
                                userId="me",
                                id=mid,
                                format="metadata",
                                metadataHeaders=["Subject", "From", "To", "Cc"],
                            )
                        )
                    else:
                        req = (
                            service.users()
                            .messages()
                            .get(userId="me", id=mid, format="full")
                        )
                    batch.add(req, request_id=mid)
    
                # Execute batch request
                await asyncio.to_thread(batch.execute)
    
            except Exception as batch_error:
                # Fallback to sequential processing instead of parallel to prevent SSL exhaustion
                logger.warning(
                    f"[get_gmail_messages_content_batch] Batch API failed, falling back to sequential processing: {batch_error}"
                )
    
                async def fetch_message_with_retry(mid: str, max_retries: int = 3):
                    """Fetch a single message with exponential backoff retry for SSL errors"""
                    for attempt in range(max_retries):
                        try:
                            if format == "metadata":
                                msg = await asyncio.to_thread(
                                    service.users()
                                    .messages()
                                    .get(
                                        userId="me",
                                        id=mid,
                                        format="metadata",
                                        metadataHeaders=["Subject", "From", "To", "Cc"],
                                    )
                                    .execute
                                )
                            else:
                                msg = await asyncio.to_thread(
                                    service.users()
                                    .messages()
                                    .get(userId="me", id=mid, format="full")
                                    .execute
                                )
                            return mid, msg, None
                        except ssl.SSLError as ssl_error:
                            if attempt < max_retries - 1:
                                # Exponential backoff: 1s, 2s, 4s
                                delay = 2 ** attempt
                                logger.warning(
                                    f"[get_gmail_messages_content_batch] SSL error for message {mid} on attempt {attempt + 1}: {ssl_error}. Retrying in {delay}s..."
                                )
                                await asyncio.sleep(delay)
                            else:
                                logger.error(
                                    f"[get_gmail_messages_content_batch] SSL error for message {mid} on final attempt: {ssl_error}"
                                )
                                return mid, None, ssl_error
                        except Exception as e:
                            return mid, None, e
    
                # Process messages sequentially with small delays to prevent connection exhaustion
                for mid in chunk_ids:
                    mid_result, msg_data, error = await fetch_message_with_retry(mid)
                    results[mid_result] = {"data": msg_data, "error": error}
                    # Brief delay between requests to allow connection cleanup
                    await asyncio.sleep(GMAIL_REQUEST_DELAY)
    
            # Process results for this chunk
            for mid in chunk_ids:
                entry = results.get(mid, {"data": None, "error": "No result"})
    
                if entry["error"]:
                    output_messages.append(f"⚠️ Message {mid}: {entry['error']}\n")
                else:
                    message = entry["data"]
                    if not message:
                        output_messages.append(f"⚠️ Message {mid}: No data returned\n")
                        continue
    
                    # Extract content based on format
                    payload = message.get("payload", {})
    
                    if format == "metadata":
                        headers = _extract_headers(payload, ["Subject", "From", "To", "Cc"])
                        subject = headers.get("Subject", "(no subject)")
                        sender = headers.get("From", "(unknown sender)")
                        to = headers.get("To", "")
                        cc = headers.get("Cc", "")
    
                        msg_output = f"Message ID: {mid}\nSubject: {subject}\nFrom: {sender}\n"
                        if to:
                            msg_output += f"To: {to}\n"
                        if cc:
                            msg_output += f"Cc: {cc}\n"
                        msg_output += f"Web Link: {_generate_gmail_web_url(mid)}\n"
    
                        output_messages.append(msg_output)
                    else:
                        # Full format - extract body too
                        headers = _extract_headers(payload, ["Subject", "From", "To", "Cc"])
                        subject = headers.get("Subject", "(no subject)")
                        sender = headers.get("From", "(unknown sender)")
                        to = headers.get("To", "")
                        cc = headers.get("Cc", "")
    
                        # Extract both text and HTML bodies using enhanced helper function
                        bodies = _extract_message_bodies(payload)
                        text_body = bodies.get("text", "")
                        html_body = bodies.get("html", "")
    
                        # Format body content with HTML fallback
                        body_data = _format_body_content(text_body, html_body)
    
                        msg_output = f"Message ID: {mid}\nSubject: {subject}\nFrom: {sender}\n"
                        if to:
                            msg_output += f"To: {to}\n"
                        if cc:
                            msg_output += f"Cc: {cc}\n"
                        msg_output += f"Web Link: {_generate_gmail_web_url(mid)}\n\n{body_data}\n"
    
                        output_messages.append(msg_output)
    
        # Combine all messages with separators
        final_output = f"Retrieved {len(message_ids)} messages:\n\n"
        final_output += "\n---\n\n".join(output_messages)
    
        return final_output
  • Helper to extract plain text and HTML bodies from Gmail message payloads by traversing MIME parts.
    def _extract_message_bodies(payload):
        """
        Helper function to extract both plain text and HTML bodies from a Gmail message payload.
    
        Args:
            payload (dict): The message payload from Gmail API
    
        Returns:
            dict: Dictionary with 'text' and 'html' keys containing body content
        """
        text_body = ""
        html_body = ""
        parts = [payload] if "parts" not in payload else payload.get("parts", [])
    
        part_queue = list(parts)  # Use a queue for BFS traversal of parts
        while part_queue:
            part = part_queue.pop(0)
            mime_type = part.get("mimeType", "")
            body_data = part.get("body", {}).get("data")
    
            if body_data:
                try:
                    decoded_data = base64.urlsafe_b64decode(body_data).decode("utf-8", errors="ignore")
                    if mime_type == "text/plain" and not text_body:
                        text_body = decoded_data
                    elif mime_type == "text/html" and not html_body:
                        html_body = decoded_data
                except Exception as e:
                    logger.warning(f"Failed to decode body part: {e}")
    
            # Add sub-parts to queue for multipart messages
            if mime_type.startswith("multipart/") and "parts" in part:
                part_queue.extend(part.get("parts", []))
    
        # Check the main payload if it has body data directly
        if payload.get("body", {}).get("data"):
            try:
                decoded_data = base64.urlsafe_b64decode(payload["body"]["data"]).decode("utf-8", errors="ignore")
                mime_type = payload.get("mimeType", "")
                if mime_type == "text/plain" and not text_body:
                    text_body = decoded_data
                elif mime_type == "text/html" and not html_body:
                    html_body = decoded_data
            except Exception as e:
                logger.warning(f"Failed to decode main payload body: {e}")
    
        return {
            "text": text_body,
            "html": html_body
        }
  • Helper to format message body content, preferring plain text over HTML with truncation for large HTML.
    def _format_body_content(text_body: str, html_body: str) -> str:
        """
        Helper function to format message body content with HTML fallback and truncation.
    
        Args:
            text_body: Plain text body content
            html_body: HTML body content
    
        Returns:
            Formatted body content string
        """
        if text_body.strip():
            return text_body
        elif html_body.strip():
            # Truncate very large HTML to keep responses manageable
            if len(html_body) > HTML_BODY_TRUNCATE_LIMIT:
                html_body = html_body[:HTML_BODY_TRUNCATE_LIMIT] + "\n\n[HTML content truncated...]"
            return f"[HTML Content Converted]\n{html_body}"
        else:
            return "[No readable content found]"
  • Helper to extract specific headers like Subject, From, To, Cc from message payload.
    def _extract_headers(payload: dict, header_names: List[str]) -> Dict[str, str]:
        """
        Extract specified headers from a Gmail message payload.
    
        Args:
            payload: The message payload from Gmail API
            header_names: List of header names to extract
    
        Returns:
            Dict mapping header names to their values
        """
        headers = {}
        for header in payload.get("headers", []):
            if header["name"] in header_names:
                headers[header["name"]] = header["value"]
        return headers
  • Helper to generate direct Gmail web interface URLs for messages/threads.
    def _generate_gmail_web_url(item_id: str, account_index: int = 0) -> str:
        """
        Generate Gmail web interface URL for a message or thread ID.
        Uses #all to access messages from any Gmail folder/label (not just inbox).
    
        Args:
            item_id: Gmail message ID or thread ID
            account_index: Google account index (default 0 for primary account)
    
        Returns:
            Gmail web interface URL that opens the message/thread in Gmail web interface
        """
        return f"https://mail.google.com/mail/u/{account_index}/#all/{item_id}"
Behavior3/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations provided, the description carries full burden. It discloses key behavioral traits: batch processing capability, 100-message limit, and Google's batch API usage. However, it doesn't mention authentication requirements, rate limits, error handling, or whether this is a read-only operation (though 'retrieves' implies reading).

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is perfectly structured and front-loaded: purpose statement first, then key constraints, followed by parameter explanations and return value. Every sentence adds value with zero waste or redundancy.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a 4-parameter tool with no annotations and no output schema, the description provides good coverage of purpose, constraints, and most parameters. The main gap is the undocumented 'service' parameter and lack of output format details beyond 'formatted list with separators'.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

With 0% schema description coverage, the description compensates well by explaining all 4 parameters: message_ids (list of IDs, max 100), user_google_email (required), and format (with clear enum explanations). However, it doesn't mention the 'service' parameter that appears in the schema, leaving one parameter undocumented.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool's purpose with specific verbs ('retrieves', 'content of multiple Gmail messages') and distinguishes it from sibling tools like get_gmail_message_content (singular) and get_gmail_thread_content. It explicitly mentions batch processing capabilities.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides clear context about when to use this tool (retrieving multiple messages in batch) and mentions the 100-message limit. However, it doesn't explicitly contrast with alternatives like get_gmail_message_content for single messages or get_gmail_thread_content for thread-based retrieval.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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