Google Contacts: Update a contact — MCP tool

Google Contacts MCP tool: Replaces chosen field groups on an existing contact with etag concurrency protection.

Technical name: update_contact

What task it solves

I want to change an existing contact's details.

Updates a contact by replacing the field groups you provide (names, emails, phones, ...) and leaving the rest untouched.

When to use it

Use it to correct or extend one saved contact. For changing many contacts the same way, use Update many contacts.

What to provide

• resource_name — required. people/c....
• etag — optional. From a recent read; fetched automatically when omitted (one extra read).
• The contact fields to replace — same vocabulary as create_contact; at least one required.

What it returns

The updated person with only the person_fields requested.

What changes in Google Contacts

Every provided group REPLACES the stored group wholesale: emails: [{...}] discards all other stored emails, emails: [] clears them, omitted groups stay untouched. Scalar fields clear on an empty value: nickname, notes and birthday with "", organization with {}. This is why the tool is marked destructive — a careless update loses data.

Example request

Change Ada's work email to ada@newco.com but first show me her current emails.

Errors and limitations

A concurrent edit between read and write fails with a 400 about the etag — re-read and retry with fresh data. Only people/c... contacts can be updated, not people/me. To append to a list, read first and send the merged list. Access also depends on token permissions, quotas, and upstream API limits.

Related MCP tools

• Get a contact — get_contact
• Update many contacts — batch_update_contacts
• Delete a contact — delete_contact

Technical details

• Impact: destructive operation
• Group: Contacts
• Description source: update_contact registration in src/tools/contacts.ts
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