How to connect Lettr to Hermes Agent
Connect Lettr to Hermes with ClawLink: paste your Lettr key once and 60 tools work from chat. No MCP server to run, nothing stored on your machine.
LettrAPI KEYMCPLettr is an email and messaging platform for transactional delivery, templates, audiences, campaigns, domains, and webhooks.. Once connected, Hermes Agent can read and act on Lettr from chat — pairing, token refresh, and tool wiring handled for you.
Most guides for giving Hermes Agent Lettr access start with registering your own OAuth app or pasting API keys into env files, then leave the token refresh and tool wiring to you. ClawLink gives Hermes a more practical Lettr setup: pair once in the browser and your always-on Hermes agent can act on Lettr for you, reading and doing real work on your behalf with no auth, token refresh, or tool wiring to build yourself.
Setup
It takes three steps to connect Hermes to Lettr.
1Install and pair
Install the ClawLink plugin, then pair Hermes with a one-time browser approval:
hermes plugins install ClawLink-HQ/hermes-plugin --enable- 2
Connect Lettr
Paste your API key in the dashboard.
- 3
Use it from chat
Ask Hermes Agent: "What can you do with Lettr?"
Install by command
The prompt above walks Hermes through this. By hand, it is four commands and a browser approval:
hermes plugins install ClawLink-HQ/hermes-plugin --enable
hermes clawlink begin # prints an approval link — open it and approve
hermes clawlink finish # after approving in the browser
hermes clawlink testThen connect Lettr in the ClawLink dashboard — paste your Lettr API key once.
Verify the connection by asking Hermes:
Pull the relevant data from Lettr, summarize it in plain English, and point out anything that needs attention.
Using a different agent?
The Hermes plugin is one client of ClawLink's MCP server. Claude Code, Cursor, Codex, or any agent that can run a shell command pairs with the same ClawLink account through the CLI:
npx -y @useclawlink/cli loginlogin opens the same browser approval and stores a credential locally. Once Lettr is connected in the dashboard, that agent calls the same 60 Lettr tools over MCP. Full setup for MCP clients and shell agents: connect apps to any AI agent.
Lettr MCP for Hermes
Looking for a Lettr MCP server for Hermes Agent? ClawLink connects Lettr to Hermes Agent and exposes 60 Lettr tools your agent can call over MCP, with hosted auth and nothing to run or maintain yourself. Using OpenClaw instead? The OpenClaw Lettr integration works the same way.
What the Hermes Agent Lettr integration can do
60 Lettr tools are ready for Hermes Agent once the account is connected. The 30 below are the ones people reach for most; your agent can call all 60.
30 of 60 Lettr tools for Hermes
| Tool | What it does |
|---|---|
Get audience contact lettr_get_audience_contact | Retrieve one contact's email, status, custom properties, list memberships, and topic |
Get audience list lettr_get_audience_list | Retrieve one audience list and its current contact count by ID |
Get audience property lettr_get_audience_property | Retrieve one custom contact-property definition and its fallback value |
Get audience segment lettr_get_audience_segment | Retrieve one dynamic segment's list restriction, complete AND-of-OR condition definition, and |
Get audience topic lettr_get_audience_topic | Retrieve one subscription topic's defaults, visibility, and current contact count |
Get campaign lettr_get_campaign | Retrieve one campaign's name, subject, sender and reply-to configuration, schedule, rendered |
Get domain lettr_get_domain | Retrieve one sending domain's send readiness, DNS records, provider detection, and verification |
Get email lettr_get_email | Retrieve a sent email's delivery state, recipients, schedule metadata, and events by request ID |
Get scheduled email lettr_get_scheduled_email | Retrieve a scheduled email's current state and events by transmission ID, including after it |
Get template lettr_get_template | Retrieve an email template's metadata, active HTML or editor JSON content, and version counts |
Get template merge tags lettr_get_template_merge_tags | Return required and optional merge tags for a template's active or specified version before |
Get webhook lettr_get_webhook | Retrieve one webhook's target, enabled state, event selection, authentication mode, and latest |
List audience contacts lettr_list_audience_contacts | Return one cursor-controlled page of contacts, optionally filtered by search text, status |
List audience lists lettr_list_audience_lists | Return one cursor-controlled page of audience lists with each list's contact count |
List audience properties lettr_list_audience_properties | Return one cursor-controlled page of custom contact-property definitions and fallback values |
List audience segments lettr_list_audience_segments | Return one cursor-controlled page of dynamic audience segments, including their complete |
List audience topics lettr_list_audience_topics | Return one cursor-controlled page of subscription topics with defaults, visibility, and contact |
List campaign events lettr_list_campaign_events | Return one cursor-controlled page of a campaign's delivery and engagement events, with event |
List campaigns lettr_list_campaigns | Return one cursor-controlled page of campaigns with complete delivery and engagement |
List domains lettr_list_domains | Return all sending domains with approval, DNS verification, and send-readiness status |
List email events lettr_list_email_events | Return one cursor-controlled page of delivery and engagement events across sent emails, with |
List emails lettr_list_emails | Return one cursor-controlled page of sent emails, optionally filtered by recipient and date |
List projects lettr_list_projects | Return one cursor-controlled page of Lettr projects and their IDs for use with template |
List templates lettr_list_templates | Return one cursor-controlled page of email templates for a project or the team's default project |
List webhooks lettr_list_webhooks | Return all event webhooks with target, enabled state, event selection, authentication mode, and |
Attach contacts to lists lettr_attach_contacts_to_lists | Attach every combination of 1-1000 contacts and 1-50 audience lists, processing up to 50,000 |
Bulk create audience contacts lettr_bulk_create_audience_contacts | Create or recognize up to 1000 normalized, deduplicated contacts |
Create audience contact lettr_create_audience_contact | Create one audience contact with optional properties and list membership |
Create audience list lettr_create_audience_list | Create a uniquely named audience list for grouping contacts |
Create audience property lettr_create_audience_property | Define a custom contact property with an immutable name and value type |
Try it: find the Lettr tool you need
Browse the 30 Lettr tools
Click any tool to see exactly what Hermes can do and copy a ready-to-use prompt.
Example prompts
Pull the relevant data from Lettr, summarize it in plain English, and point out anything that needs attention.
Pull the relevant data from Lettr, summarize it in plain English, and point out anything that needs attention.
Pull the relevant data from Lettr, summarize it in plain English, and point out anything that needs attention.
Pull the relevant data from Lettr, summarize it in plain English, and point out anything that needs attention.
ClawLink vs. building it yourself
The alternative to ClawLink is usually manual API key setup plus your own token handling, permission troubleshooting, and tool plumbing for Hermes Agent. That is fine if you want to build and maintain the integration yourself. Most teams just want Lettr working from chat.
| Manual | ClawLink | |
|---|---|---|
| Credential handling | Collect, validate, store, and rotate the Lettr API key yourself, then make sure every tool call uses the right account. | Users complete the hosted ClawLink setup once and the connected Lettr account becomes available to the agent without you building credential management. |
| Ongoing maintenance | You own refresh logic, permission debugging, environment config, and every provider-specific edge case for Lettr. | ClawLink handles the repetitive integration plumbing so your team can focus on the workflow instead of the infrastructure. |
| Agent usability | You still need to expose the right Lettr actions to the runtime in a format your agent can reliably use. | 60 tools for Lettr are already exposed through ClawLink, so the agent can read and act from chat immediately. |
ClawLink vs. Composio
Composio also exposes Lettr to AI agents. It is developer infrastructure: Python and TypeScript SDKs, an MCP server, and a catalog past 1,000 apps, aimed at teams shipping agent products. ClawLink is built for Hermes Agent users instead. You install the plugin once, connect Lettr in the browser, and the 60 tools above work from chat. There is no SDK and no config file, and the Lettr key you paste at setup is stored server-side rather than kept in your environment. Choosing between them? Read the full Composio alternatives comparison.
Troubleshooting
Hermes paired but still can't use Lettr
Pairing is a two-step handshake: run hermes clawlink begin, approve the link in your browser, then run hermes clawlink finish. If you ran finish before approving, or the approval link expired, run hermes clawlink begin again to get a fresh link. Confirm the plugin was installed with --enable, then verify with hermes clawlink test.
Connection succeeds but no tools appear
Reconnect Lettr from the dashboard, then start a fresh chat if the runtime still has the old tool catalog loaded.
"Tool schema not loaded yet" error when calling Lettr tools
Lettr tool schemas load on demand the first time a tool runs and are cached after that, so this error usually clears on its own: wait a few seconds and retry the same request. If every Lettr call keeps failing with it in a fresh chat, reconnect from the dashboard, and contact support if it still persists — that pattern points to a configuration problem on our side, not something you can fix by reconnecting again.
Lettr returns 403 or "permission denied" on one action while others work
Two usual causes. The connected account may not have access to the specific workspace, inbox, store, or project in the request — check that first. If access looks right, the agent may have sent a placeholder value (like "YOUR_ID" or an example id from documentation) instead of a real one: ask it to run a list or search tool first, then retry the action with a real id from those results. Most failures at this stage are one of these two, not ClawLink bugs.
API key setup works but results look incomplete
Double-check that the API key for Lettr has the right scopes or account access. A valid key can still be too limited for some reads or writes.
FAQ
Is there a Hermes Agent Lettr integration?
Yes. ClawLink is the fastest way to connect Hermes to Lettr: link your Lettr account once in the browser and Hermes Agent can call the Lettr API through 60 ready-made tools — no custom code or token handling.
How do I connect Lettr to Hermes with ClawLink?
Install the plugin with hermes plugins install ClawLink-HQ/hermes-plugin --enable, then pair once: run hermes clawlink begin, approve the link in your browser, and run hermes clawlink finish. Connect Lettr in the dashboard and Hermes can use it from the next message — no config files, and the Lettr key you paste is stored server-side instead of in your environment.
How long does it take to connect Lettr to Hermes Agent?
About two minutes. Sign in, click Connect next to Lettr in the dashboard, authenticate, and Hermes Agent can use it from the next chat message.
Why use ClawLink instead of wiring Lettr up myself?
The alternative to ClawLink is usually manual API key setup plus your own token handling, permission troubleshooting, and tool plumbing for Hermes Agent. That is fine if you want to build and maintain the integration yourself. Most teams just want Lettr working from chat.
Hermes paired but still can't use Lettr
Pairing is a two-step handshake: run hermes clawlink begin, approve the link in your browser, then run hermes clawlink finish. If you ran finish before approving, or the approval link expired, run hermes clawlink begin again to get a fresh link. Confirm the plugin was installed with --enable, then verify with hermes clawlink test.
