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people.contactGroups.members.modify

Add or remove contacts from a contact group owned by the authenticated user. Supports system groups like myContacts and starred for additions, and removals from deprecated groups.

Instructions

Modify the members of a contact group owned by the authenticated user. The only system contact groups that can have members added are contactGroups/myContacts and contactGroups/starred. Other system contact groups are deprecated and can only have contacts removed [HTTP POST] — creates or triggers a change; refused under --readonly safety profiles. Returns the API's response resource as JSON — request body is a JSON ModifyContactGroupMembersRequest object accepting resourceNamesToAdd, resourceNamesToRemove; pass it via params or whole via body_file

Input Schema

Name	Required	Description
`query`	No	Extra KEY=VALUE query pairs for endpoints whose parameters Discovery does not describe.
`params`	No	Parameter map merged into the request; typed parameters win.
`dry_run`	No	Return the request that would be sent, without sending it.
`body_file`	No	Read the request body from this file ('-' for stdin) instead of building one from the parameters. The body is a JSON ModifyContactGroupMembersRequest object.
`request_body`	No	Request body of type ModifyContactGroupMembersRequest: pass it via `params` (merged into the built body) or whole via `body_file`.
`resourceName`	Yes	[URL path segment] Required. The resource name of the contact group to modify.

Output Schema

Name	Required	Description	Default
`notFoundResourceNames`	No
`canNotRemoveLastContactGroupResourceNames`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedOct 26, 2026

changedInput schema / properties / body_file / description

Previous value: -"Read the request body from this file ('-' for stdin) instead of building one from the parameters."New value: +"Read the request body from this file ('-' for stdin) instead of building one from the parameters. The body is a JSON ModifyContactGroupMembersRequest object."

addedInput schema / properties / request_body

Added value: +{
+  "description": "Request body of type ModifyContactGroupMembersRequest: pass it via `params` (merged into the built body) or whole via `body_file`.",
+  "properties": {
+    "resourceNamesToAdd": {
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    },
+    "resourceNamesToRemove": {
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    }
+  },
+  "type": "object"
+}

Changed3 schema fields changedOct 26, 2026

changedInput schema / properties / resourceName / description

Previous value: -"Required. The resource name of the contact group to modify."New value: +"[URL path segment] Required. The resource name of the contact group to modify."

addedInput schema / properties / resourceName / pattern
```
Added value: +"^contactGroups/[^/]+$"
```

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "properties": {
+    "canNotRemoveLastContactGroupResourceNames": {
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    },
+    "notFoundResourceNames": {
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    }
+  },
+  "type": "object"
+}

First observedOct 26, 2026

TDQS

A4/5.0

Behavior4/5

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

With no annotations, the description carries the burden well: it flags this as an HTTP POST that 'creates or triggers a change' and notes it is 'refused under --readonly safety profiles,' which is exactly the mutation/safety context an agent needs. It also states the return is the API's response resource as JSON. Minor gap: no detail on permission scope beyond the system-group constraints.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Purpose is front-loaded, then system-group constraints, then mutability/safety, then body details. Every clause carries information, though the bracketed/dashed run-on phrasing is dense and slightly harder to parse than a cleanly segmented version.

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

Completeness4/5

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

Given the tool has an output schema (so return values needn't be detailed) and no annotations, the description fills the important gaps: usage preconditions, mutation safety-profile refusal, and body-passing options. It is complete enough to call correctly; only finer permission/edge-case detail is absent.

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

Parameters4/5

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

Schema coverage is 100% so the baseline is 3; the description adds practical routing by naming resourceNamesToAdd/resourceNamesToRemove and explaining they can be passed via `params` or whole via `body_file`. This clarifies the body-passing mechanic beyond the schema's field definitions.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb ('Modify') and resource ('the members of a contact group') and clarifies ownership ('owned by the authenticated user'), so it is distinguishable from sibling CRUD operations like contactGroups.update/create/delete. It stops short of explicitly contrasting with those siblings, keeping it at a 4 rather than 5.

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?

Provides concrete preconditions: only `contactGroups/myContacts` and `contactGroups/starred` can have members added, and other system groups allow removal only. This is clear usage context. It does not explicitly route the agent among alternatives (e.g., vs. contactGroups.update), so not a 5.

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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