---
title: "POST /v1/projects/{projectsId}/locations/{locationsId}/studies/{studiesId}/trials:suggest"
method: POST
path: "/v1/projects/{projectsId}/locations/{locationsId}/studies/{studiesId}/trials:suggest"
tags: ["projects"]
---

# POST /v1/projects/{projectsId}/locations/{locationsId}/studies/{studiesId}/trials:suggest

`POST /v1/projects/{projectsId}/locations/{locationsId}/studies/{studiesId}/trials:suggest`

## Request

- Base URL: `https://aiplatform.googleapis.com`
- URL: `https://aiplatform.googleapis.com/v1/projects/{projectsId}/locations/{locationsId}/studies/{studiesId}/trials:suggest`
- Auth: OAuth 2 and OAuth 2
  - Implicit: `https://accounts.google.com/o/oauth2/auth`
  - Scopes: `https://www.googleapis.com/auth/cloud-platform`
  - Authorization code: `https://accounts.google.com/o/oauth2/auth`
  - Token URL: `https://accounts.google.com/o/oauth2/token` scopes: `https://www.googleapis.com/auth/cloud-platform`

Adds one or more Trials to a Study, with parameter values suggested by Vertex AI Vizier. Returns a long-running operation associated with the generation of Trial suggestions. When this long-running operation succeeds, it will contain a SuggestTrialsResponse.

## Path parameters

- `projectsId` string, required
- `locationsId` string, required
- `studiesId` string, required

## Request body

- GoogleCloudAiplatformV1SuggestTrialsRequest: Request message for VizierService.SuggestTrials.
  - `clientId` string: Required. The identifier of the client that is requesting the suggestion. If multiple SuggestTrialsRequests have the same `client_id`, the service will return the identical suggested Trial if the Trial is pending, and provide a new Trial if the last suggested Trial was completed.
  - `contexts` GoogleCloudAiplatformV1TrialContext[]: Optional. This allows you to specify the "context" for a Trial; a context is a slice (a subspace) of the search space. Typical uses for contexts: 1) You are using Vizier to tune a server for best performance, but there's a strong weekly cycle. The context specifies the day-of-week. This allows Tuesday to generalize from Wednesday without assuming that everything is identical. 2) Imagine you're optimizing some medical treatment for people. As they walk in the door, you know certain facts about them (e.g. sex, weight, height, blood-pressure). Put that information in the context, and Vizier will adapt its suggestions to the patient. 3) You want to do a fair A/B test efficiently. Specify the "A" and "B" conditions as contexts, and Vizier will generalize between "A" and "B" conditions. If they are similar, this will allow Vizier to converge to the optimum faster than if "A" and "B" were separate Studies. NOTE: You can also enter contexts as REQUESTED Trials, e.g. via the CreateTrial() RPC; that's the asynchronous option where you don't need a close association between contexts and suggestions. NOTE: All the Parameters you set in a context MUST be defined in the Study. NOTE: You must supply 0 or $suggestion_count contexts. If you don't supply any contexts, Vizier will make suggestions from the full search space specified in the StudySpec; if you supply a full set of context, each suggestion will match the corresponding context. NOTE: A Context with no features set matches anything, and allows suggestions from the full search space. NOTE: Contexts MUST lie within the search space specified in the StudySpec. It's an error if they don't. NOTE: Contexts preferentially match ACTIVE then REQUESTED trials before new suggestions are generated. NOTE: Generation of suggestions involves a match between a Context and (optionally) a REQUESTED trial; if that match is not fully specified, a suggestion will be geneated in the merged subspace.
    - `description` string: A human-readable field which can store a description of this context. This will become part of the resulting Trial's description field.
    - `parameters` GoogleCloudAiplatformV1TrialParameter[]: If/when a Trial is generated or selected from this Context, its Parameters will match any parameters specified here. (I.e. if this context specifies parameter name:'a' int_value:3, then a resulting Trial will have int_value:3 for its parameter named 'a'.) Note that we first attempt to match existing REQUESTED Trials with contexts, and if there are no matches, we generate suggestions in the subspace defined by the parameters specified here. NOTE: a Context without any Parameters matches the entire feasible search space.
      - `parameterId` string: Output only. The ID of the parameter. The parameter should be defined in StudySpec's Parameters.
      - `value` unknown
  - `suggestionCount` integer: Required. The number of suggestions requested. It must be positive.

## Response `200`

Successful response

- GoogleLongrunningOperation: This resource represents a long-running operation that is the result of a network API call.
  - `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.
  - `error` GoogleRpcStatus: The `Status` type defines a logical error model that is suitable for different programming environments, including REST APIs and RPC APIs. It is used by [gRPC](https://github.com/grpc). Each `Status` message contains three pieces of data: error code, error message, and error details. You can find out more about this error model and how to work with it in the [API Design Guide](https://cloud.google.com/apis/design/errors).
    - `code` integer: The status code, which should be an enum value of google.rpc.Code.
    - `details` object[]: A list of messages that carry the error details. There is a common set of message types for APIs to use.
    - `message` string: A developer-facing error message, which should be in English. Any user-facing error message should be localized and sent in the google.rpc.Status.details field, or localized by the client.
  - `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.
  - `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}`.
  - `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`.

---

[API](https://skmtc.dev/google/apis/aiplatform.md) - [All operations](https://skmtc.dev/google/apis/aiplatform/llms.txt) - [OpenAPI document](https://skmtc.dev/google/apis/aiplatform/revisions/3aca3b348f0c?raw)