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Email Sending MCP

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Update Automation

update-automation

Update an automation's name, status, or workflow to control email sending sequences.

Instructions

Purpose: Update an automation's name, status, or workflow.

When to use:

  • User wants to rename an automation

  • User wants to enable or disable an automation (use status: "disabled" to stop it)

  • User wants to modify the workflow steps

Important:

  • To disable/stop an automation, set status to "disabled". Existing runs will continue to completion.

  • When updating the workflow, provide the complete new workflow — it replaces the existing one.

  • Use get-automation first to see the current workflow before making changes.

The workflow is a JSON object with one key: "steps" — an array of step objects.

Each step has: key (unique string), type, config, and either "next" (string|null) or "branches" (for branching steps). Use keys like: "trigger", "send_email_1", "delay_1", "condition_1", "wait_event_1".

Step types

trigger — starts the automation when an event fires (required, exactly one)

config: { "eventName": "" } Uses "next".

send_email — send an email using a published template

config: { "template": { "id": "", "variables": { "": "" } }, "from": "Name sender@example.com", "subject": "Email subject", "replyTo": "" } "from" and "subject" are resolved from the step config first, then fall back to the template. If neither provides a "from", the email will silently fail to send. If neither provides a "subject", the run will error. Best practice: always set "from" and "subject" on the step config so the automation is self-contained. Use list-domains to find verified domains for "from". "replyTo" and "variables" are optional. Variables can use { "var": "event." } or { "var": "contact." } for dynamic values. Uses "next".

delay — pause the workflow

config: { "duration": "" } Examples: "30 minutes", "1 hour", "2 days", "1 week". Max 30 days. Uses "next".

condition — conditional split based on contact or event data

config: A condition rule object: Single rule: { "type": "rule", "field": "event." or "contact.", "operator": "", "value": } Compound: { "type": "and"|"or", "rules": [, ...] } Operators: eq, neq, gt, gte, lt, lte, contains, starts_with, ends_with, exists, is_empty. exists/is_empty do not require a value. Uses "branches": { "condition_met": "", "condition_not_met": "" }

wait_for_event — pause until a specific event arrives or timeout

config: { "eventName": "", "timeout": "", "filterRule": } For email lifecycle events use "resend:email.<opened|clicked|bounced|delivered|complained|failed|suppressed>". Uses "branches": { "event_received": "", "timeout": "" }

contact_update — update contact fields

config: { "firstName": "", "lastName": "", "unsubscribed": true|false, "properties": { "": "" } } All fields optional. Values can use { "var": "event." } for dynamic data. Uses "next".

contact_delete — remove the contact from the audience

config: {} Uses "next".

add_to_segment — add contact to a segment

config: { "segmentId": "" } Uses "next".

Rules

  1. Every step must be reachable from the trigger via next/branches.

  2. Terminal steps have "next": null (or null branch values).

  3. The workflow must be tree-shaped — no merging branches back together.

Example: Linear drip campaign

{ "steps": [ { "key": "trigger", "type": "trigger", "config": { "eventName": "user.created" }, "next": "send_email_1" }, { "key": "send_email_1", "type": "send_email", "config": { "template": { "id": "tmpl_123" }, "from": "Welcome hello@example.com", "subject": "Welcome!" }, "next": "delay_1" }, { "key": "delay_1", "type": "delay", "config": { "duration": "3 days" }, "next": "send_email_2" }, { "key": "send_email_2", "type": "send_email", "config": { "template": { "id": "tmpl_456" }, "from": "Welcome hello@example.com", "subject": "Getting started" }, "next": null } ] }

Example: Re-engagement with wait_for_event

{ "steps": [ { "key": "trigger", "type": "trigger", "config": { "eventName": "user.created" }, "next": "send_email_1" }, { "key": "send_email_1", "type": "send_email", "config": { "template": { "id": "tmpl_789" }, "from": "Team team@example.com", "subject": "Welcome" }, "next": "wait_event_1" }, { "key": "wait_event_1", "type": "wait_for_event", "config": { "eventName": "resend:email.opened", "timeout": "3 days" }, "branches": { "event_received": null, "timeout": "send_email_2" } }, { "key": "send_email_2", "type": "send_email", "config": { "template": { "id": "tmpl_abc" }, "from": "Team team@example.com", "subject": "Did you miss this?" }, "next": null } ] }

Example: Condition branch

{ "steps": [ { "key": "trigger", "type": "trigger", "config": { "eventName": "trial.ended" }, "next": "condition_1" }, { "key": "condition_1", "type": "condition", "config": { "type": "rule", "field": "event.converted", "operator": "eq", "value": true }, "branches": { "condition_met": "send_email_1", "condition_not_met": "send_email_2" } }, { "key": "send_email_1", "type": "send_email", "config": { "template": { "id": "tmpl_thanks" }, "from": "Team team@example.com", "subject": "Thanks for upgrading!" }, "next": null }, { "key": "send_email_2", "type": "send_email", "config": { "template": { "id": "tmpl_win_back" }, "from": "Team team@example.com", "subject": "We'd love to have you back" }, "next": null } ] }

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
idYesAutomation ID or Resend dashboard URL (e.g. https://resend.com/automations/<id>)
nameNoNew name for the automation.
statusNoNew status. Use "disabled" to stop the automation (prevents new runs).
workflowNoNew workflow definition. Replaces the existing workflow entirely.
Behavior5/5

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

With no annotations provided, the description fully carries the behavioral disclosure. It reveals important behaviors such as disabled status not stopping existing runs, workflow replacement semantics, potential silent email failures, and constraints like reachability and tree-shaped workflows. This is far beyond generic mutation behavior.

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 long but every section earns its place: purpose, when-to-use, important notes, step-type reference, rules, and three illustrative examples. It is front-loaded with action and use-case context before diving into detailed reference material, with no filler or redundancy.

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

Completeness5/5

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

For a complex tool managing automation workflows, the description covers all necessary context: step types, configs, branching semantics, constraints, examples, and potential failure modes. No output schema exists, but the operational guidance is so thorough that the lack of return-value documentation is not a meaningful gap in this context.

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

Parameters5/5

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

Although schema coverage is 100%, the description adds substantial meaning beyond the schema's basic parameter definitions. It provides a comprehensive guide to the workflow parameter, including every step type, config structure, branching rules, and worked examples. It also clarifies id/status/name usage in context, making parameter interpretation much richer.

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 opens with 'Update an automation's name, status, or workflow,' clearly specifying the verb and the modifiable resources. It distinguishes itself from siblings like create-automation and remove-automation by enumerating the exact update operations it supports.

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 'When to use' section lists precise scenarios: renaming, toggling status, and modifying workflow steps. It also advises calling get-automation first to inspect the current workflow. However, it does not explicitly name alternative tools for create/delete or state 'do not use' conditions, so full when/when-not guidance is slightly lacking.

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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