Mail MCP Server
Provides tools for sending and receiving emails via Gmail's SMTP and IMAP servers, including email composition, mailbox management, and search.
Click on "Deploy Server".
Wait a few minutes for the server to deploy. Once ready, it will show a "Started" state.
In the chat, type
@followed by the MCP server name and your instructions, e.g., "@Mail MCP Serversend an email to alice@example.com with subject 'Meeting' and body 'See you tomorrow.'"
That's it! The server will respond to your query, and you can continue using it as needed.
Here is a step-by-step guide with screenshots.
Mail MCP Server
A Model Context Protocol (MCP) server for SMTP and IMAP-based email handling. This server enables AI assistants to send and read emails, manage mailboxes, and handle email configurations securely.
Features
Sending Emails (SMTP)
Send Emails: Send emails with HTML/plain text content, attachments, and CC/BCC support
Connection Verification: Test SMTP connection and authentication
Configuration Testing: Test custom SMTP configurations without modifying server settings
Reading Emails (IMAP)
Fetch Emails: Retrieve emails from any mailbox with filtering options
Search Emails: Simple search by subject, sender, or content
Advanced Search: Complex queries with multiple criteria (sender, recipient, date range, size, flags)
List Mailboxes: Browse all available folders/mailboxes
Mark Emails: Mark emails as read/unread or flagged/unflagged
Email Organization
Create/Delete Mailboxes: Manage folder structure
Move Messages: Organize emails between folders
Copy Messages: Duplicate emails to multiple folders
Save Drafts: Store draft emails for later editing
Advanced Features
Thread View: Get entire conversation threads with chronological ordering
Download Attachments: Retrieve specific attachments with base64 encoding
Message Relationships: Track reply chains via Message-ID, In-Reply-To, and References headers
Security
Secure: All credentials managed via environment variables
TLS Support: Encrypted connections for both SMTP and IMAP
Related MCP server: mcp-imap
Installation
npm install
npm run buildConfiguration
Required Environment Variables
# SMTP Configuration (for sending emails)
export SMTP_HOST="smtp.gmail.com" # SMTP server hostname
export SMTP_PORT="587" # SMTP server port (587 or 465)
export SMTP_USER="your-email@gmail.com" # SMTP username
export SMTP_PASS="your-app-password" # SMTP password
export SMTP_FROM="your-email@gmail.com" # (Optional) Default sender address
export SMTP_SECURE="false" # (Optional) Use TLS (true for port 465)Optional IMAP Configuration (for reading emails)
If not provided, IMAP settings default to SMTP values:
export IMAP_HOST="imap.gmail.com" # IMAP server (defaults to SMTP_HOST)
export IMAP_PORT="993" # IMAP port (default: 993)
export IMAP_USER="your-email@gmail.com" # IMAP username (defaults to SMTP_USER)
export IMAP_PASS="your-app-password" # IMAP password (defaults to SMTP_PASS)
export IMAP_TLS="true" # Use TLS (default: true)Usage
Running the Server
Stdio Transport (Default)
For use with Claude Desktop or other stdio-based clients:
# Without .env
npm run dev
# With .env file
npm run dev:envSSE Transport (HTTP/Server-Sent Events)
For web-based clients or remote connections:
# Start SSE server on port 3000
TRANSPORT=sse npm run dev:sse:env
# Or custom port
TRANSPORT=sse PORT=8080 npm run dev:sse:envThe server will be available at:
MCP endpoint:
http://localhost:3000/mcpSSE endpoint:
http://localhost:3000/sse
Environment Variables for SSE:
TRANSPORT=sse- Enable SSE transportPORT=3000- HTTP server port (default: 3000)SSE_PATH=/sse- SSE endpoint path (default: /sse)
Using with Claude Desktop (Stdio)
Add to your Claude Desktop configuration file:
macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
Windows: %APPDATA%\Claude\claude_desktop_config.json
{
"mcpServers": {
"mail": {
"command": "npx",
"args": ["-y", "martinzarfl/mail-mcp"],
"env": {
"SMTP_HOST": "smtp.provider.com",
"SMTP_PORT": "587",
"SMTP_USER": "your-email@provider.com",
"SMTP_PASS": "your-mail-password",
"SMTP_FROM": "your-email@provider.com",
"IMAP_HOST": "imap.provider.com",
"IMAP_PORT": "993",
"IMAP_USER": "your-email@provider.com",
"IMAP_PASS": "your-mail-password"
}
}
}
}Available Tools
SMTP Tools (Sending Emails)
send_email
Send an email via SMTP.
Parameters:
to(required): Recipient email addresssubject(required): Email subject linetext(optional): Plain text email bodyhtml(optional): HTML email bodyfrom(optional): Sender email address (uses SMTP_FROM if not provided)cc(optional): CC recipient email addressbcc(optional): BCC recipient email addressattachments(optional): Array of attachments withfilename,content, andencoding(base64 or utf-8)
Example:
{
"to": "recipient@example.com",
"subject": "Hello from MCP",
"text": "This is a test email",
"html": "<h1>This is a test email</h1>"
}verify_connection
Verify the SMTP connection and authentication using configured credentials.
Parameters: None
test_smtp_config
Test SMTP configuration with custom credentials without modifying the server configuration.
Parameters:
host(required): SMTP server hostnameport(required): SMTP server portuser(required): SMTP authentication usernamepassword(required): SMTP authentication passwordsecure(optional): Use TLS (default: true for port 465)
get_smtp_info
Get information about the current SMTP configuration (without revealing credentials).
Parameters: None
IMAP Tools (Reading Emails)
list_mailboxes
List all available mailboxes/folders in the IMAP account.
Parameters: None
Example Response:
{
"success": true,
"mailboxes": [
{"name": "INBOX", "delimiter": "/", "children": 0},
{"name": "Sent", "delimiter": "/", "children": 0},
{"name": "Drafts", "delimiter": "/", "children": 0}
],
"count": 3
}fetch_emails
Fetch emails from a specific mailbox with optional filters.
Parameters:
mailbox(optional): Mailbox name (default: "INBOX")limit(optional): Maximum emails to fetch, 1-100 (default: 10)unseen(optional): Only fetch unread emails (default: false)since(optional): Only fetch emails since date (ISO 8601 format)
Example:
{
"mailbox": "INBOX",
"limit": 5,
"unseen": true
}search_emails
Search for emails in a mailbox by subject, sender, or content.
Parameters:
mailbox(optional): Mailbox name (default: "INBOX")query(required): Search query stringlimit(optional): Maximum results, 1-100 (default: 10)
Example:
{
"query": "meeting",
"limit": 10
}mark_email
Mark an email with a specific flag.
Parameters:
mailbox(optional): Mailbox name (default: "INBOX")uid(required): Email UID to markflag(required): Flag to set ("read", "unread", "flagged", "unflagged")
Example:
{
"uid": 123,
"flag": "read"
}Advanced IMAP Tools
create_mailbox
Create a new mailbox/folder in your email account.
Parameters:
name(required): Name of the mailbox to create
Example:
{
"name": "Projects"
}delete_mailbox
Delete a mailbox/folder from your email account.
Parameters:
name(required): Name of the mailbox to delete
Example:
{
"name": "OldFolder"
}move_message
Move an email from one mailbox to another.
Parameters:
sourceMailbox(optional): Source mailbox (default: "INBOX")targetMailbox(required): Target mailbox nameuid(required): Email UID to move
Example:
{
"sourceMailbox": "INBOX",
"targetMailbox": "Archive",
"uid": 123
}copy_message
Copy an email from one mailbox to another.
Parameters:
sourceMailbox(optional): Source mailbox (default: "INBOX")targetMailbox(required): Target mailbox nameuid(required): Email UID to copy
Example:
{
"targetMailbox": "Important",
"uid": 456
}advanced_search
Search emails with multiple criteria including sender, recipient, subject, body, date range, size, and flags.
Parameters:
mailbox(optional): Mailbox name (default: "INBOX")criteria(required): Search criteria object with fields:from: Search by senderto: Search by recipientsubject: Search by subject textbody: Search by body textsince: Date filter (ISO 8601)before: Date filter (ISO 8601)unseen: Only unread emails (boolean)flagged: Only flagged emails (boolean)larger: Minimum size in bytessmaller: Maximum size in bytes
limit(optional): Maximum results, 1-100 (default: 10)
Example:
{
"criteria": {
"from": "boss@company.com",
"since": "2025-01-01",
"unseen": true
},
"limit": 20
}save_draft
Save an email as a draft in the Drafts folder without sending it.
Parameters:
to(required): Recipient email addresssubject(required): Email subjecttext(optional): Plain text bodyhtml(optional): HTML bodyfrom(optional): Sender addresscc(optional): CC recipientbcc(optional): BCC recipient
Example:
{
"to": "colleague@company.com",
"subject": "Draft: Project Update",
"text": "This is a draft email..."
}get_thread
Get all emails in a conversation thread based on a message ID. Returns emails sorted chronologically with reply relationships.
Parameters:
mailbox(optional): Mailbox name (default: "INBOX")messageId(required): Message ID to find thread for
Example:
{
"messageId": "<abc123@mail.example.com>"
}Response includes:
messageId: Unique message identifierinReplyTo: Parent message IDreferences: All related message IDsFull email content sorted by date
download_attachment
Download a specific attachment from an email. Returns the attachment content as base64-encoded data.
Parameters:
mailbox(optional): Mailbox name (default: "INBOX")uid(required): Email UIDattachmentIndex(required): Attachment index (0-based)
Example:
{
"uid": 789,
"attachmentIndex": 0
}Response:
{
"success": true,
"filename": "report.pdf",
"contentType": "application/pdf",
"size": 102400,
"content": "JVBERi0xLjQKJeLjz9MKM...",
"encoding": "base64"
}Development
# Build the project
npm run build
# Watch for changes
npm run watch
# Run in development mode
npm run devSecurity Notes
Never commit credentials to version control
Use environment variables for sensitive data
Consider using App Passwords instead of regular passwords
Use TLS/SSL for secure connections (port 465 or STARTTLS on 587)
Common Email Providers
Provider | SMTP Host | SMTP Port | IMAP Host | IMAP Port |
Gmail | smtp.gmail.com | 587/465 | imap.gmail.com | 993 |
Outlook | smtp-mail.outlook.com | 587 | outlook.office365.com | 993 |
Yahoo | smtp.mail.yahoo.com | 587 | imap.mail.yahoo.com | 993 |
iCloud | smtp.mail.me.com | 587 | imap.mail.me.com | 993 |
SendGrid | smtp.sendgrid.net | 587 | N/A | N/A |
Notes:
Port 587: Use with STARTTLS (set
SMTP_SECURE="false")Port 465: Use with SSL/TLS (set
SMTP_SECURE="true")Port 993: Standard IMAP over SSL/TLS
License
MIT
Available Tools
16 toolsadvanced_searchB
Advanced email search with multiple criteria (from, to, subject, body, date range, size, flags).
| Name | Required | Description | Default |
|---|---|---|---|
| limit | No | Maximum number of results (1-100, default: 10) | |
| mailbox | No | Mailbox name (default: INBOX) | |
| criteria | Yes | Search criteria |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the transparency burden. However, it only enumerates search criteria already present in the schema and adds no information about side effects, authorization, return format, pagination, or mailbox scope. It is not misleading but adds minimal behavioral context beyond the schema.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Single sentence, no filler, front-loaded with the core purpose. It is concise and readable.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a tool with no annotations, no output schema, and sibling search tools, the description is under-specified. It doesn't clarify default behavior (limit, mailbox), result format, or when to prefer it over search_emails. However, the schema covers parameter details, making the description minimally viable.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, with each parameter documented. The description merely summarizes the criteria as 'date range, size, flags' without adding new syntax or constraints, so it meets the baseline but does not exceed it.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly identifies this as an advanced email search tool with multiple filter criteria. The verb 'search' and resource 'email' are explicit, and listing criteria (from, to, subject, body, date range, size, flags) distinguishes it from basic search tools, though without naming sibling tools.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description provides no guidance on when to use this tool versus simpler alternatives like search_emails or fetch_emails. The word 'advanced' implies a distinction, but no explicit usage context or exclusions are given.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
copy_messageA
Copy an email from one mailbox to another.
| Name | Required | Description | Default |
|---|---|---|---|
| uid | Yes | Email UID to copy | |
| sourceMailbox | No | Source mailbox name (default: INBOX) | |
| targetMailbox | Yes | Target mailbox name |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden of behavioral disclosure. It states the action but does not disclose whether the source email is preserved, whether message flags are copied, permissions required, or any side effects. This is a significant gap for a mutation tool.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single sentence with no redundant words. It directly communicates the tool's purpose without fluff, making it appropriately concise and well-structured.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple copy operation with well-documented parameters, the description is adequate but not complete. It lacks context about prerequisites, return values, or behavioral nuances. Given no annotations or output schema, there are clear gaps that could affect an agent's decision to use the tool correctly.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The input schema has 100% coverage, with descriptions for uid, sourceMailbox, and targetMailbox. The description adds no additional parameter semantics beyond what the schema already provides, so a baseline score of 3 applies.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description 'Copy an email from one mailbox to another' clearly identifies the verb (copy), resource (email), and scope (from one mailbox to another). This distinguishes it from sibling tools like move_message, which implies moving (and thus removing) rather than duplicating.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description implies a use case (duplicating an email between mailboxes) but does not explicitly state when to use this tool over alternatives. It lacks guidance on conditions like preserving the original, and it doesn't name or exclude sibling tools such as move_message.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
create_mailboxB
Create a new mailbox/folder in the IMAP account.
| Name | Required | Description | Default |
|---|---|---|---|
| name | Yes | Name of the mailbox to create |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description must carry full behavioral disclosure. It only states the action without revealing what happens on duplicate names, whether parent folders are auto-created, permission requirements, or any side effects. For a mutating operation, this is insufficient transparency.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single concise sentence that is front-loaded with the action and resource. There is no wasted wording, and it is appropriately sized for a simple tool with one parameter.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Although the tool is simple with one parameter, the description lacks essential context such as behavior on duplicate mailboxes, whether the operation is idempotent, or how it integrates with the IMAP account's existing folder hierarchy. With no output schema and no annotations, the description is too sparse to fully inform an agent.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The schema already describes the 'name' parameter 100% (coverage is high), so the baseline is 3. The description adds no additional meaning about naming conventions, allowed characters, or path syntax beyond the schema's simple 'Name of the mailbox to create'. It neither compensates nor detracts.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description uses the specific verb 'Create' and clearly names the resource 'new mailbox/folder in the IMAP account', distinguishing it from sibling tools like list_mailboxes and delete_mailbox. It is unambiguous about the operation being performed.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description gives no guidance on when to use this tool versus alternatives. It does not mention situations where creating a mailbox is appropriate, nor does it exclude cases like existing mailboxes or name restrictions. This leaves the agent to infer usage context.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
delete_mailboxB
Delete a mailbox/folder from the IMAP account.
| Name | Required | Description | Default |
|---|---|---|---|
| name | Yes | Name of the mailbox to delete |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden of disclosing behavioral traits. It states the action (delete) but does not mention irreversibility, potential side effects (e.g., messages lost), or any permissions required. This is a significant gap for a destructive operation.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single, clear sentence with no redundant wording. It is effectively front-loaded, stating the action and resource immediately.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The tool is simple with one parameter and no output schema, but the description lacks context about edge cases (e.g., deleting a non-empty mailbox) or error conditions. It is minimally viable but could benefit from a note about consequences or constraints.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The input schema already describes the 'name' parameter as 'Name of the mailbox to delete', so schema coverage is 100%. The description adds no additional meaning beyond the schema, which is acceptable given the single, self-explanatory parameter.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description uses a specific verb ('Delete') and clearly identifies the resource ('mailbox/folder from the IMAP account'). It distinguishes itself from sibling tools like create_mailbox and list_mailboxes by stating the delete action.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description provides no guidance on when to use this tool versus alternatives, nor does it mention prerequisites, exclusions, or conditions under which deletion is appropriate. The agent must infer usage from the tool name and schema alone.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
download_attachmentA
Download a specific attachment from an email. Returns base64-encoded content.
| Name | Required | Description | Default |
|---|---|---|---|
| uid | Yes | Email UID | |
| mailbox | No | Mailbox name (default: INBOX) | |
| attachmentIndex | Yes | Attachment index (0-based) |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It discloses that the output is base64-encoded content, which is useful. However, it does not mention side effects (or lack thereof), prerequisites, error conditions, or limitations like file size, which would enhance transparency.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single, concise sentence that front-loads the action and resource. It avoids redundancy and contains no fluff, making it highly efficient.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple download tool with full schema coverage and no output schema, the description is mostly complete. It states the return format (base64) and covers the core functionality, though it could add details about error handling or indexing edge cases.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100% with descriptions for all three parameters (uid, mailbox, attachmentIndex). The description adds no additional parameter semantics, so the baseline score of 3 is appropriate.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description explicitly states 'Download a specific attachment from an email,' clearly identifying the verb and resource. This distinguishes it from sibling tools like fetch_emails or search_emails by focusing on the specific action of retrieving an attachment.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
No explicit when-to-use or alternative guidance is given. However, the tool's purpose is self-evident from the name and description, implying usage when a specific attachment needs to be downloaded. This is acceptable but lacks explicit differentiation from potential overlaps.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
fetch_emailsC
Fetch emails from a specific mailbox. Returns email metadata and content.
| Name | Required | Description | Default |
|---|---|---|---|
| limit | No | Maximum number of emails to fetch (1-100, default: 10) | |
| since | No | Only fetch emails since this date (ISO 8601 format) | |
| unseen | No | Only fetch unread emails (default: false) | |
| mailbox | No | Mailbox name (default: INBOX) |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description must convey behavioral traits. It only states that it fetches and returns data, but does not disclose side effects (e.g., marking reads, pagination, sorting, or effects on mailbox state). This is a significant gap for a tool that may mutate read status.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is two concise sentences with no redundancy. It is front-loaded with the action and resource, then states the return value. Every word earns its place.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The tool has no output schema and no annotations, yet the description does not explain return format, pagination, limits, or ordering. It also lacks guidance on when to use it relative to other tools. For a tool with four parameters and no annotations, this is insufficient contextual information.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema descriptions cover 100% of parameters, so the description adds little value beyond the schema. The description does not explain how parameters interact or the meaning of 'since', 'unseen', etc., beyond their schema descriptions. Baseline 3 is appropriate.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the action (Fetch emails) and the resource (specific mailbox), and mentions what is returned (metadata and content). It is specific and understandable, though it does not explicitly differentiate from sibling tools like search_emails or advanced_search.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
No guidance is provided on when to use this tool versus alternatives such as search_emails or get_thread. There is no mention of context, prerequisites, or exclusions, leaving the agent without decision support.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
get_smtp_infoB
Get information about the current SMTP configuration (without revealing credentials).
| Name | Required | Description | Default |
|---|---|---|---|
No parameters | |||
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the transparency burden. It discloses that credentials are not revealed, which is a useful behavioral trait. However, it does not describe what is returned or any side effects, but the tool is likely read-only. The single safety note earns a moderate score.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is one concise sentence, well-front-loaded, with no wasted words.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given the tool's simplicity with no parameters and no output schema, the description provides a basic summary but lacks specifics on return fields or operational details. It is minimally complete but could be more informative.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
There are zero parameters, so the schema is trivially covered. The description adds context by clarifying 'SMTP configuration' as the subject, earning a baseline of 4.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states that the tool retrieves SMTP configuration information, using a specific verb and resource. It also adds a safety qualifier about credentials, but it does not explicitly differentiate from sibling tools like verify_connection or test_smtp_config, so it's clear but without explicit sibling differentiation.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description provides no guidance on when to use this tool versus its siblings. It simply states what it does, leaving the agent to infer usage. No alternatives or exclusions are mentioned.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
get_threadA
Get all emails in a conversation thread based on a message ID. Returns emails sorted chronologically.
| Name | Required | Description | Default |
|---|---|---|---|
| mailbox | No | Mailbox name (default: INBOX) | |
| messageId | Yes | Message ID to find thread for |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
There are no annotations provided, so the description carries the full burden of behavioral disclosure. It does disclose that emails are returned 'sorted chronologically,' which is a useful behavioral trait. However, it does not explicitly state that the operation is read-only or non-destructive, although the verb 'Get' implies this. The description could be more transparent about side effects or permissions, but for a simple read operation, the disclosed sorting behavior provides partial value.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is concise, consisting of two short sentences that are front-loaded with the main action ('Get all emails in a conversation thread') and supplemented with a key detail ('Returns emails sorted chronologically'). Every word earns its place, with no redundancy or filler.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given the low complexity (2 parameters, no output schema), the description is fairly complete. It states the core functionality, the input basis (message ID), and the return behavior (sorted emails). It does not cover error cases or edge conditions, but for a simple retrieval tool, this is acceptable. The absence of an output schema is partially compensated by the return description.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, as both parameters (mailbox and messageId) are described in the input schema. The description adds minimal meaning beyond the schema: it confirms that messageId is the key for finding the thread, but does not elaborate on default values, formats, or relationships between parameters. With full schema coverage, the baseline of 3 is appropriate.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states what the tool does: 'Get all emails in a conversation thread based on a message ID.' This is a specific verb+resource combination that distinguishes it from sibling tools like fetch_emails (which likely retrieves emails from a mailbox) and search_emails (which searches for emails). The mention of 'thread' and 'message ID' adds critical context.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description does not provide explicit guidance on when to use this tool versus alternatives. It implies you need a message ID, but does not state prerequisites, nor does it contrast with fetch_emails or search_emails. No when-to-use or when-not-to-use scenarios are mentioned, leaving the agent to infer the appropriate context.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
list_mailboxesA
List all available mailboxes/folders in the IMAP account.
| Name | Required | Description | Default |
|---|---|---|---|
No parameters | |||
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries full responsibility for behavioral disclosure. It does not state that the operation is read-only, any authentication requirements, or what happens with an empty account or server errors. This is a minimal description with no behavioral traits beyond the obvious action.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single, front-loaded sentence that efficiently conveys the tool's purpose without any wasted words.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given the tool's simplicity (no parameters, no output schema), the description is largely complete for a listing operation. It would benefit from stating the return format (e.g., array of folder names), but it adequately conveys the scope and purpose for the agent.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The tool has zero parameters, so the parameter semantics are trivially satisfied. The schema description coverage is 100% with an empty properties object, and the description adds no unnecessary parameter information.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description uses specific verb 'List' and identifies the resource as 'mailboxes/folders in the IMAP account', distinguishing it from sibling tools like create_mailbox or delete_mailbox. It clearly states the scope as 'all available'.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description clearly indicates the tool's purpose for enumerating mailboxes/folders, providing adequate context for when to use it. However, it does not explicitly mention alternative tools or exclusions, leaving some room for agent interpretation.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
mark_emailB
Mark an email with a specific flag (read/unread/flagged/unflagged).
| Name | Required | Description | Default |
|---|---|---|---|
| uid | Yes | Email UID to mark | |
| flag | Yes | Flag to set on the email | |
| mailbox | No | Mailbox name (default: INBOX) |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden of behavioral disclosure. It implies a mutation (marking an email) but does not mention side effects, permanence, permission requirements, or error behavior. The description adds no context beyond what the schema already encodes.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single, front-loaded sentence that immediately conveys the action and the accepted flags. It is concise with no wasted words, making it easy to parse and understand.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The tool is relatively simple with a fully descriptive schema, but the description lacks any contextual detail about side effects, return behavior, or usage scenarios. For a mutation tool without annotations, this is a clear gap, though the schema covers parameter meaning, leaving the overall description minimally viable.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so the baseline is 3. The description does not add extra meaning beyond the schema; it merely restates the flag values that are already defined in the enum. No additional parameter semantics are provided.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the tool's function: marking an email with a specific flag, listing the exact flag values (read/unread/flagged/unflagged). This uses a specific verb ('mark') and resource ('email'), distinguishing it from siblings like fetch_emails or move_message.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description provides no guidance on when to use this tool versus alternatives such as move_message or copy_message. It does not specify prerequisites, typical use cases, or exclusions. The sibling list suggests context, but the description itself lacks any usage direction.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
move_messageB
Move an email from one mailbox to another.
| Name | Required | Description | Default |
|---|---|---|---|
| uid | Yes | Email UID to move | |
| sourceMailbox | No | Source mailbox name (default: INBOX) | |
| targetMailbox | Yes | Target mailbox name |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description must disclose behavioral traits, but it only says 'Move an email from one mailbox to another.' It does not explicitly state that the message is removed from the source mailbox, nor does it mention permissions, reversibility, or error handling.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single, clear sentence with no unnecessary words. It is concise and front-loaded with the action.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The tool is simple, and the description adequately states its core purpose. However, without annotations or an output schema, it leaves gaps about behavioral details and usage context, such as when to prefer move over copy.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The schema already provides descriptions for all three parameters, so the description adds no extra parameter semantics. This is the baseline for full schema coverage.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description uses a specific verb 'Move' and clearly identifies the resource: an email from one mailbox to another. This distinguishes it from sibling tool copy_message, which implies copying rather than moving.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description provides no guidance on when to use this tool versus alternatives like copy_message or fetch_emails. It also does not mention any prerequisites or context for use.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
save_draftC
Save an email as a draft in the Drafts folder.
| Name | Required | Description | Default |
|---|---|---|---|
| cc | No | CC recipient (optional) | |
| to | Yes | Recipient email address | |
| bcc | No | BCC recipient (optional) | |
| from | No | Sender email address (optional) | |
| html | No | HTML email body (optional) | |
| text | No | Plain text email body | |
| subject | Yes | Email subject |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It only discloses the action and destination. It does not mention required permissions, whether the draft is saved locally or on the server, idempotency, or what is returned after saving. This is insufficient for a mutation tool.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single, focused sentence with no filler words. It immediately communicates the tool's purpose without redundancy, earning a top score for conciseness.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Despite having 7 parameters, no annotations, and no output schema, the description is extremely brief. It does not clarify behavior related to sending, attachments, server interaction, or result handling. This leaves significant gaps for an agent trying to use the tool correctly.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so parameter semantics are fully handled by the schema. The description adds no additional meaning beyond what the schema already provides, making the baseline score of 3 appropriate.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the action (Save), the resource (an email), and the destination (Drafts folder). It implies a non-sending action, which helps distinguish it from sibling tools like send_email, though it doesn't explicitly name alternatives.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
No guidance is provided on when to use this tool versus alternatives such as send_email, test_smtp_config, or move_message. The description simply states what the tool does without any contextual or conditional advice.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
search_emailsB
Search for emails in a mailbox using a search query (searches in subject, from, and body).
| Name | Required | Description | Default |
|---|---|---|---|
| limit | No | Maximum number of results (1-100, default: 10) | |
| query | Yes | Search query string | |
| mailbox | No | Mailbox name (default: INBOX) |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It discloses the search fields (subject, from, body), which is beyond the schema, but does not mention sorting, pagination, case sensitivity, or read-only behavior. Adds some context but leaves gaps.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single, front-loaded sentence that directly states the purpose and scope. There is no redundant or filler content, making it highly concise and well-structured.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The tool has no output schema, and the description does not explain the return format or pagination behavior. The schema covers parameters, but the description lacks enough detail to fully inform an agent of expected outputs or edge cases.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The input schema already describes all three parameters (query, limit, mailbox) with 100% coverage. The description adds only the search-scope context, not parameter-specific details. Baseline 3 is appropriate.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the tool searches for emails using a search query and specifies the scope (subject, from, body). However, it does not explicitly distinguish it from sibling tools like advanced_search or fetch_emails, so it lacks explicit differentiation.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
There is no guidance on when to use this tool versus alternatives such as advanced_search or fetch_emails. The description implies a general search use but provides no context for selection or exclusion.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
send_emailA
Send an email via SMTP. Supports HTML and plain text content, attachments, and CC/BCC recipients.
| Name | Required | Description | Default |
|---|---|---|---|
| cc | No | CC recipient email address (optional) | |
| to | Yes | Recipient email address | |
| bcc | No | BCC recipient email address (optional) | |
| from | No | Sender email address (optional, uses SMTP_FROM env var if not provided) | |
| html | No | HTML email body (optional, overrides text if provided) | |
| text | No | Plain text email body | |
| subject | Yes | Email subject line | |
| attachments | No | Email attachments (optional) |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden. It discloses supported content types and recipient options, which adds useful context. However, it does not mention prerequisites like SMTP authentication, side effects, or what happens after sending.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is two sentences, front-loading the primary action and listing key capabilities without redundancy. Every sentence earns its place, and the structure is clean and direct.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The schema thoroughly documents parameters, and the description covers the main purpose and supported features. Since there is no output schema, the description does not clarify return values or error behavior, but this is a minor gap for a straightforward send operation.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The input schema has 100% parameter coverage with descriptions for all 8 parameters. The description adds no additional meaning beyond what the schema already provides, so the baseline score of 3 is appropriate.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description uses a specific verb ('Send') and a clear resource ('email via SMTP'), making the tool's function immediately obvious. It also lists key features (HTML, plain text, attachments, CC/BCC) that distinguish it from sibling tools like fetch_emails or test_smtp_config.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description does not explicitly state when to use this tool vs alternatives, nor does it mention exclusions. The intended usage is implied by the verb 'Send', but there is no guidance to help the agent choose it over other email-related tools.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
test_smtp_configA
Test SMTP configuration with custom credentials without modifying the server configuration.
| Name | Required | Description | Default |
|---|---|---|---|
| host | Yes | SMTP server hostname | |
| port | Yes | SMTP server port | |
| user | Yes | SMTP authentication username | |
| secure | No | Use TLS (default: true for port 465) | |
| password | Yes | SMTP authentication password |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description takes on the responsibility of disclosing side effects. It explicitly states 'without modifying the server configuration', which is a key behavioral trait that assures the tool is non-destructive. It could further explain what the test actually does (e.g., sends a probe email or only checks authentication) but the core safety guarantee is clear.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single concise sentence, front-loaded with the verb 'Test'. It conveys the tool's purpose and a critical constraint in minimal words. There is no redundancy or filler, making it easy to parse.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The tool is relatively simple with fully documented parameters and a clear purpose. The only notable gap is the absence of an output schema and any description of return values, which could leave the agent uncertain about what success/failure looks like. However, the name and description imply a test result, and the overall context is sufficient for invocation.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The input schema has 100% description coverage for all 5 parameters, so the baseline is 3. The description adds little extra parameter meaning beyond referring to 'custom credentials', which maps loosely to user/password but does not clarify details like secure's default behavior. The schema adequately covers semantics.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly identifies the tool's action ('Test'), the resource ('SMTP configuration'), and a specific scope ('with custom credentials without modifying the server configuration'). This distinguishes it from sibling tools like send_email or verify_connection by emphasizing the no-side-effect testing aspect.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description implies a usage context: testing SMTP settings using custom credentials without altering the server. However, it does not explicitly state when to prefer this over alternatives like verify_connection, nor does it provide any 'when not to use' guidance. The usage is inferred rather than explicit.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
verify_connectionB
Verify the SMTP connection and authentication using configured credentials.
| Name | Required | Description | Default |
|---|---|---|---|
No parameters | |||
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description is the sole source of behavioral context. It states that the tool 'verifies' the connection and authentication, implying a read-only test, but does not explicitly confirm it is non-destructive, describe any side effects, or explain what happens on success or failure. The term 'verify' is suggestive but does not fully disclose behavior.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single, focused sentence that immediately states the tool's purpose. It wastes no words and is easy to parse.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a zero-parameter tool with no output schema, the description covers the core functionality but leaves some contextual gaps. Specifically, it doesn't clarify how 'verify_connection' differs from the sibling tool 'test_smtp_config,' and it doesn't specify the result format or any preconditions. This is enough for basic understanding but not fully complete for an AI to select with confidence.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The tool takes zero parameters, so the schema is trivially covered at 100%. The description does not need to add parameter details, and it correctly avoids inventing any. A baseline score of 4 is warranted given the absence of parameters.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description uses the verb 'verify' with a clear resource ('SMTP connection and authentication') and references 'configured credentials,' making the tool's function apparent. However, it does not distinguish itself from the sibling 'test_smtp_config,' which likely serves a similar purpose, so it stops short of a 5.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description provides no guidance on when to use this tool versus alternatives like test_smtp_config or send_email. There is no mention of preferred scenarios, prerequisites, or exclusions, leaving the agent to infer selection.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Tool Schema Changelog
Recent tool additions, removals, and schema changes observed during successful MCP inspections.
16 tool updates
v1.0.2- First observed
advanced_search - First observed
copy_message - First observed
create_mailbox - First observed
delete_mailbox - First observed
download_attachment - First observed
fetch_emails - First observed
get_smtp_info - First observed
get_thread - First observed
list_mailboxes - First observed
mark_email - First observed
move_message - First observed
save_draft - First observed
search_emails - First observed
send_email - First observed
test_smtp_config - First observed
verify_connection
TDQS
Scored across 16 tools
Several tools have overlapping purposes: `search_emails` and `advanced_search` both search, with `advanced_search` being a superset; `test_smtp_config` and `verify_connection` both verify SMTP connectivity; `fetch_emails` and `search_emails` have unclear boundaries. The descriptions help but do not fully resolve the ambiguity.
Tool names consistently follow a `verb_noun` pattern with underscores (e.g., `send_email`, `list_mailboxes`, `move_message`). Even multi-word actions like `test_smtp_config` and `get_smtp_info` maintain the pattern. Naming is uniform and predictable.
With 16 tools, the server is slightly above the ideal 3-15 range but still feels scoped to email functionality. Each tool addresses a distinct operation, though some could be consolidated (e.g., search tools, connection verification).
The server covers sending, retrieving, searching, mailbox management, attachments, and drafts. Notable gaps include no direct email deletion operation (though moving to trash is possible) and no explicit update draft operation. These are minor and mostly workaroundable.
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