Tools Reference

This reference lists every tool on Lettr’s remote MCP server, grouped by what it works on. Each tool does exactly what the matching API endpoint does, and your AI client receives each tool’s full input schema when it connects, so you never have to pass parameters by hand. Just describe what you want. The deprecated local server (lettr-mcp npm package) offers the same tools with a few differences, listed under Local server differences. It is no longer updated, so anything added below exists only on the hosted server.

Destructive Tools and Permissions

Tools marked Destructive send email, overwrite data, or remove data in a way that can’t be undone. They carry the MCP destructive annotation, so clients such as Claude can ask you before running them. Read-only tools are annotated as read-only. Every tool runs as you, in the team you choose (see Choosing a Team), and goes through the same team permission checks as the dashboard. The AI can never reach another team’s domains, templates, contacts, or campaigns.

A confirmation prompt is only as good as your review of it. Before approving a destructive tool, check the recipients, the audience, and the IDs it is about to act on, especially for send_campaign and the bulk audience tools.

Emails

Tool	What it does	Destructive
`send_email`	Send an email with HTML, plain text, or AMP HTML content, with optional merge tags	Yes
`send_template_email`	Send an email using a saved template, identified by its slug	Yes
`list_emails`	List recently sent emails with filters and cursor pagination	—
`get_email_detail`	Show one sent email’s full delivery timeline by its request ID	—

Both send tools accept an idempotency_key. When the AI reuses the same key on a retry, the email is not sent twice (see Idempotency). Sent emails stay in list_emails for about 10 days.

Scheduled Emails

Tool	What it does	Destructive
`schedule_email`	Schedule an email for later delivery, with the same content options as `send_email`	—
`get_scheduled_email`	Show a scheduled email’s state, delivery time, sender, subject, and recipients	—
`cancel_scheduled_email`	Cancel a scheduled email before it is sent	Yes

The delivery time must be at least 5 minutes and at most 30 days in the future. See the Schedule Email endpoint for the full set of options.

Templates, Folders, and Projects

Tool	What it does	Destructive
`list_projects`	List your team’s projects, the containers for templates and folders	—
`list_folders`	List the template folders in a project, each with its purpose	—
`list_templates`	List templates, filtered by project, purpose, or folder	—
`get_template`	Show a template’s details by ID or slug	—
`get_template_html`	Get the rendered HTML, subject, and merge tags of a template’s active version	—
`get_merge_tags`	List the merge tags a template expects, and which are required	—
`create_template`	Create a Custom HTML template	—
`update_template`	Replace a template’s content and make the result the new active version	Yes
`delete_template`	Permanently delete a template and all its versions	Yes

create_template takes a purpose of transactional (the default) or campaign, and the purpose can’t be changed later. A campaign can only send a campaign template, so ask for a campaign template when you’re writing a newsletter or promotion.

Sending Domains

Tool	What it does	Destructive
`list_sending_domains`	List sending domains with their verification status	—
`get_domain`	Show a sending domain’s DNS status and the DKIM record to publish	—
`create_domain`	Register a new sending domain and return the DNS records to publish	—
`verify_domain`	Run DNS verification for a sending domain and store the result	—
`delete_domain`	Delete a sending domain, which stops all sending from it	Yes
`diagnose_sending_domain_dns`	Explain why a domain is still pending or failing verification, and whether to wait or fix a record	—

Other Domains

Tool	What it does	Destructive
`list_tracking_domains`	List the branded domains used for open and click tracking	—
`list_inbound_domains`	List the domains set up to receive email, with each domain’s MX verification status and when it was added. Read-only: it doesn’t show the forwarding URL, create inbound domains, or read received messages	—
`list_storage_domains`	List the domains that serve stored email content	—

Webhooks

Tool	What it does	Destructive
`list_webhooks`	List webhooks with their URL, event types, and delivery health	—
`get_webhook`	Show one webhook’s configuration and last delivery times	—
`create_webhook`	Create a webhook for all events or selected ones, with optional basic or OAuth 2.0 auth	—
`update_webhook`	Change a webhook’s settings; only the fields you give change	Yes
`delete_webhook`	Delete a webhook, which stops event delivery right away	Yes

Campaigns

Tool	What it does	Destructive
`list_campaigns`	List campaigns with engagement stats, optionally filtered by status	—
`get_campaign`	Show one campaign with its stats, rendered HTML, and language overrides	—
`list_campaign_events`	List a campaign’s opens, clicks, bounces, and other events	—
`send_campaign`	Send a draft campaign to its whole audience right away	Yes
`schedule_campaign`	Schedule a draft campaign, or move an already scheduled one to a new time	Yes
`unschedule_campaign`	Cancel a scheduled send and return the campaign to draft	—

send_campaign and schedule_campaign send real email to every recipient in the campaign’s audience. Emails that have gone out can’t be recalled.

Audience

Contacts

Tool	What it does	Destructive
`list_audience_contacts`	List contacts, filtered by search text, status, list, or segment	—
`get_audience_contact`	Show a contact with its status, properties, lists, and topics	—
`create_audience_contact`	Create a single contact	—
`bulk_create_audience_contacts`	Create many contacts in one call and report any rows that were skipped	—
`update_audience_contact`	Update a contact; only the fields you give change	Yes
`delete_audience_contact`	Delete a contact and remove it from all lists and topics	Yes

Lists

Tool	What it does	Destructive
`list_audience_lists`	List your team’s contact lists	—
`get_audience_list`	Show one list with its contact count	—
`create_audience_list`	Create a list	—
`update_audience_list`	Rename a list	Yes
`delete_audience_list`	Delete a list; its contacts are kept but detached	Yes
`bulk_delete_audience_lists`	Delete several lists in one call	Yes
`attach_contact_to_list`	Add one contact to one list	—
`detach_contact_from_list`	Remove one contact from one list; the contact is kept	Yes
`bulk_attach_contacts_to_lists`	Add every given contact to every given list	—
`bulk_detach_contacts_from_lists`	Remove every given contact from every given list	Yes

Topics

Tool	What it does	Destructive
`list_audience_topics`	List your team’s subscription topics	—
`get_audience_topic`	Show one topic	—
`create_audience_topic`	Create a topic with an opt-in or opt-out default	—
`update_audience_topic`	Update a topic; its default subscription can’t change	Yes
`delete_audience_topic`	Delete a topic and all subscriptions to it	Yes
`subscribe_contact_to_topic`	Subscribe one contact to one topic	—
`unsubscribe_contact_from_topic`	Unsubscribe one contact from one topic	Yes
`bulk_subscribe_contacts_to_topics`	Subscribe every given contact to every given topic	—
`bulk_unsubscribe_contacts_from_topics`	Unsubscribe every given contact from every given topic	Yes

Properties

Tool	What it does	Destructive
`list_audience_properties`	List the custom contact properties defined for your team	—
`get_audience_property`	Show one property	—
`create_audience_property`	Define a new custom property	—
`update_audience_property`	Change a property’s fallback value or purpose	Yes
`delete_audience_property`	Delete a property and its value from every contact	Yes

Segments

Tool	What it does	Destructive
`list_audience_segments`	List segments, optionally only those restricted to a list	—
`get_audience_segment`	Show a segment’s conditions and contact count	—
`create_audience_segment`	Create a segment from match conditions	—
`update_audience_segment`	Update a segment; new conditions replace the old set	Yes
`delete_audience_segment`	Delete a segment; its contacts are kept	Yes

For how contacts, lists, topics, properties, and segments fit together, see Audience.

Analytics and Monitoring

Tool	What it does	Destructive
`check_sending_health`	Give one verdict on your sending health from domains, delivery trends, and recent problems	—
`get_analytics`	Show delivery totals and a daily breakdown for a period	—
`list_template_stats`	Show delivery statistics per template	—
`browse_email_events`	Browse delivery events such as deliveries, opens, clicks, and bounces	—
`browse_api_logs`	Browse API request logs, filtered by key, client, or status code	—

Account

Tool	What it does	Destructive
`list_teams`	List the teams this connection can act on	—
`current_team`	Show which team a call would act on, and how it was chosen	—
`list_api_keys`	List your team’s API keys by name and prefix, with their permissions (never the full key)	—

Local Server Differences

The local lettr-mcp package is no longer updated. It names its tools with hyphens instead of underscores (send-email instead of send_email) and uses different names for some parameters (contactId rather than contact_id), so a configuration moving to the hosted server needs both adjusted. Otherwise it offers the same tools, with these exceptions:

Remote server	Local server
`send_template_email`	No separate tool; `send-email` takes a `template_slug`
`list_sending_domains`	`list-domains`
`browse_email_events`	`list-email-events`
`check_sending_health`, `diagnose_sending_domain_dns`	Not available
`get_analytics`, `list_template_stats`, `browse_api_logs`	Not available
`list_tracking_domains`, `list_inbound_domains`, `list_storage_domains`, `list_api_keys`	Not available
Not available	`list-scheduled-emails` lists emails waiting to be sent
Not available	`auth-check` validates the configured API key
Not available	`health-check` checks the Lettr API status

Remote Server Setup

Connect via OAuth from Claude, ChatGPT, Cursor, and other AI clients

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API Reference

Full REST API documentation

Template Language

Merge tag syntax and template variables

Documentation

Quickstart

Learn

Integrations

Resources

Tools Reference

Destructive Tools and Permissions

Emails

Scheduled Emails

Templates, Folders, and Projects

Sending Domains

Other Domains

Webhooks

Campaigns

Audience

Contacts

Lists

Topics

Properties

Segments

Analytics and Monitoring

Account

Local Server Differences

Remote Server Setup

Connect with an API Key

API Reference

Template Language

​Destructive Tools and Permissions

​Emails

​Scheduled Emails

​Templates, Folders, and Projects

​Sending Domains

​Other Domains

​Webhooks

​Campaigns

​Audience

​Contacts

​Lists

​Topics

​Properties

​Segments

​Analytics and Monitoring

​Account

​Local Server Differences

​Related Topics

Remote Server Setup

Connect with an API Key

API Reference

Template Language

Destructive Tools and Permissions

Emails

Scheduled Emails

Templates, Folders, and Projects

Sending Domains

Other Domains

Webhooks

Campaigns

Audience

Contacts

Lists

Topics

Properties

Segments

Analytics and Monitoring

Account

Local Server Differences

Related Topics