Tool: create_instance
Creates an AlloyDB instance, which is a child resource of a cluster.
Requirements
- The cluster that the instance is being created in must exist and be in a READY state. You can use the
list_clusterstool to list all clusters in a project. - If you're trying to create a PRIMARY instance, then the cluster must not already have a PRIMARY instance.
- If you're trying to create a READ_POOL instance, then the cluster must already have a PRIMARY instance.
Usage
- Call
create_clusterto create a cluster if it doesn't exist. - Call
create_instanceto create an instance within the cluster. - This will return a long-running operation that indicates the progress of the instance creation.
- You can poll the status of the operation using the
get_operationtool. Generally the creation takes 5-10 minutes. - Once the long-running operation is complete, the instance will be in a READY state.
The following sample demonstrate how to use curl
to invoke the create_instance
MCP tool.
| Curl Request |
|---|
curl --location 'https://alloydb.googleapis.com/mcp' \ --header 'content-type: application/json' \ --header 'accept: application/json, text/event-stream' \ --data '{ "method": "tools/call", "params": { "name": "create_instance", "arguments": { // provide these details according to the tool' s MCP specification } } , "jsonrpc" : "2.0" , "id" : 1 } ' |
Input Schema
Message for creating an instance.
CreateInstanceRequest
| JSON representation |
|---|
{ "parent" : string , "instanceId" : string , "type" : string , // Union field |
parent
string
Required. Identifier. The parent resource in which to create the instance. The value must have a format of projects/{project}/locations/{location}/clusters/{cluster_id}. - {project} is the project that the cluster resides in. This field can be specified either as: - Project ID: An alphanumeric string that can consist of lowercase letters, numerical digits, or dash ("-") characters. - Project number: A valid base-10 encoded positive integer. - {location} is the Google Cloud region that the cluster resides in. Regions will have format like "us-central1" or "us-west2". - {cluster_id} is the ID of cluster. It should be an alphanumeric string that can consist of lowercase letters, numerical digits, or dash ("-") characters. The field is REQUIRED.
instanceId
string
Required. The instance ID is the unique user-assigned ID of the instance. It should be an alphanumeric string that can consist of lowercase letters, numerical digits, or dash characters ("-"). This field is REQUIRED.
type
string
Optional. The type of the instance. The allowed values are: - PRIMARY - An AlloyDB instance that will accept both read and write Postgres transactions. You can have only one primary instance per cluster. - READ_POOL - An AlloyDB instance that will only accept read Postgres transactions. You can have multiple read pool instances per cluster, but they can only be created after the primary instance has been created. This field is OPTIONAL. If unspecified, it will default to PRIMARY.
Union field _cpu_count
.
_cpu_count
can be only one of the following:
cpuCount
integer
Optional. The number of CPUs for the instance. If unspecified, it will default to 4. This field is OPTIONAL.
Union field _machine_type
.
_machine_type
can be only one of the following:
machineType
string
Optional. The machine type of the instance. If unspecified, it will default to n2-highmem-4. This field is OPTIONAL.
Union field _readpool_node_count
.
_readpool_node_count
can be only one of the following:
readpoolNodeCount
integer
Optional. The number of read pool nodes for the instance. If unspecified, it will default to 1. This field is OPTIONAL.
Union field _db_iam_authentication
.
_db_iam_authentication
can be only one of the following:
dbIamAuthentication
boolean
Optional. Enables DB IAM authentication for this instance. Sets the "alloydb.iam_authentication" db flag to "on"/"off". This field is OPTIONAL. If unspecified, it will default to true.
Output Schema
This resource represents a long-running operation that is the result of a network API call.
Operation
| JSON representation |
|---|
{ "name" : string , "metadata" : { "@type" : string , field1 : ... , ... } , "done" : boolean , // Union field |
name
string
The server-assigned name, which is only unique within the same service that originally returns it. If you use the default HTTP mapping, the name
should be a resource name ending with operations/{unique_id}
.
metadata
object
Service-specific metadata associated with the operation. It typically contains progress information and common metadata such as create time. Some services might not provide such metadata. Any method that returns a long-running operation should document the metadata type, if any.
An object containing fields of an arbitrary type. An additional field "@type"
contains a URI identifying the type. Example: { "id": 1234, "@type": "types.example.com/standard/id" }
.
done
boolean
If the value is false
, it means the operation is still in progress. If true
, the operation is completed, and either error
or response
is available.
result
. The operation result, which can be either an error
or a valid response
. If done
== false
, neither error
nor response
is set. If done
== true
, exactly one of error
or response
can be set. Some services might not provide the result. result
can be only one of the following:error
object (
Status
)
The error result of the operation in case of failure or cancellation.
response
object
The normal, successful response of the operation. If the original method returns no data on success, such as Delete
, the response is google.protobuf.Empty
. If the original method is standard Get
/ Create
/ Update
, the response should be the resource. For other methods, the response should have the type XxxResponse
, where Xxx
is the original method name. For example, if the original method name is TakeSnapshot()
, the inferred response type is TakeSnapshotResponse
.
An object containing fields of an arbitrary type. An additional field "@type"
contains a URI identifying the type. Example: { "id": 1234, "@type": "types.example.com/standard/id" }
.
Any
| JSON representation |
|---|
{ "typeUrl" : string , "value" : string } |
| Fields | |
|---|---|
typeUrl
|
Identifies the type of the serialized Protobuf message with a URI reference consisting of a prefix ending in a slash and the fully-qualified type name. Example: type.googleapis.com/google.protobuf.StringValue This string must contain at least one The prefix is arbitrary and Protobuf implementations are expected to simply strip off everything up to and including the last All type URL strings must be legal URI references with the additional restriction (for the text format) that the content of the reference must consist only of alphanumeric characters, percent-encoded escapes, and characters in the following set (not including the outer backticks): In the original design of |
value
|
Holds a Protobuf serialization of the type described by type_url. A base64-encoded string. |
Status
| JSON representation |
|---|
{ "code" : integer , "message" : string , "details" : [ { "@type" : string , field1 : ... , ... } ] } |
| Fields | |
|---|---|
code
|
The status code, which should be an enum value of |
message
|
A developer-facing error message, which should be in English. Any user-facing error message should be localized and sent in the |
details[]
|
A list of messages that carry the error details. There is a common set of message types for APIs to use. An object containing fields of an arbitrary type. An additional field |
Tool Annotations
Destructive Hint: ❌ | Idempotent Hint: ✅ | Read Only Hint: ❌ | Open World Hint: ✅

