DEADLETTER◆ Documentation
Everything you need to connect your agents to Deadletter.
You can be running in under 5 minutes.
- 1.Sign up at deadletter.ca/sign-up with your Google account.
- 2.Create a project from the dashboard. Give it a name like
my-project. - 3.Generate an API key from the Overview page. Name it after the machine (e.g.
cursor-laptop). - 4.Add MCP config to your agent (see below).
- 5.Your agent can now read and write context. That's it.
Add this block to your ~/.cursor/mcp.json (Cursor) or your agent framework's MCP server config:
{
"mcpServers": {
"deadletter": {
"url": "https://mcp.deadletter.ca/mcp",
"headers": {
"Authorization": "Bearer YOUR_API_KEY"
}
}
}
}Replace YOUR_API_KEY with the key you generated. You can copy the exact config block (with your key pre-filled) from the Overview page in the dashboard after generating a key.
Claude Desktop: Add the same block under mcpServers in ~/Library/Application Support/Claude/claude_desktop_config.json.
Once connected, your agent has access to the following MCP tools:
create_projectCreate a new shared context project. You become the owner.list_projectsList all projects you are a member of (name, ID, your role).get_projectGet full details of a project including members and file list.write_fileCreate or overwrite a shared file in a project. Requires Writer or Owner role.read_fileRead a shared file from a project by path.list_filesList all files in a project with metadata.delete_fileDelete a file from a project. Requires Writer or Owner role.send_messageSend a message to anyone by name or email. Creates a shared project, writes the content, and notifies them via Slack or email.invite_to_projectInvite someone to a project by email or Slack handle. They get a link to join.remove_memberRemove a member from a project, or leave a project yourself.rename_projectRename a project you own.list_contactsList people in your network (org members and past collaborators).search_usersFuzzy search for users across your org and contacts by name or email.Your agent discovers these tools automatically when it connects to the MCP server — no setup beyond the config block required.
Projects are named namespaces. Each project has members with one of three roles:
Invite collaborators by email from the project detail page. They'll receive an invite link. You can also invite via Slack DM if you've connected Slack.
API keys authenticate your agents to the MCP server. Best practices:
- ›Create one key per machine or agent, named clearly (e.g. 'macbook', 'cursor-work', 'ci-bot').
- ›Keys are shown only once at creation — copy them immediately.
- ›Revoke keys you no longer use. Revocation is instant.
- ›Never commit keys to source control. Use environment variables or secret stores.
Connect Slack from Settings → Slack in the dashboard. Once connected:
- ›You get a Slack DM whenever someone's agent writes a file to a shared project you're in.
- ›You get a Slack DM when someone sends you a message via the send_message tool.
- ›Notifications are per-project — mute noisy projects from the project detail page.
- ›Slack integration is per-user (not per-workspace). Each collaborator connects individually.