Bedrock Agent function resolver¶

Implement functions for a Bedrock Agent Action Group and return tool results to the agent.

Install¶

Use Go 1.27 or newer:

CGO_ENABLED=0 go get github.com/rambow-cloud/powertools-lambda-go/eventhandler/bedrock@v1.2.0
CGO_ENABLED=0 go get github.com/aws/aws-lambda-go@v1.55.0

Create a greeting tool¶

Configure a function-based Action Group with a greeting function and a string parameter named name.

Input

Call greeting with the string parameter name=Ada.

Complete Lambda event

{
  "messageVersion": "1.0",
  "agent": {
    "name": "orders-agent",
    "id": "AGENT12345",
    "alias": "ALIAS12345",
    "version": "DRAFT"
  },
  "inputText": "Greet Ada",
  "sessionId": "example-session",
  "actionGroup": "orders",
  "function": "greeting",
  "parameters": [
    {
      "name": "name",
      "type": "string",
      "value": "Ada"
    }
  ],
  "sessionAttributes": {},
  "promptSessionAttributes": {}
}

Code

package main

import (
    "context"
    "fmt"

    "github.com/aws/aws-lambda-go/lambda"
    "github.com/rambow-cloud/powertools-lambda-go/eventhandler/bedrock"
)

func main() {
    app := bedrock.New(bedrock.Options{})
    app.Tool(func(ctx context.Context, params *bedrock.Parameters, event bedrock.Event) (any, error) {
        return bedrock.NewFunctionResponse(fmt.Sprintf("Hello, %v", params.Get("name"))), nil
    }, bedrock.Configuration{Name: "greeting"})
    lambda.Start(app.Resolve)
}

Output

{
  "messageVersion": "1.0",
  "response": {
    "actionGroup": "orders",
    "function": "greeting",
    "functionResponse": {
      "responseBody": {
        "TEXT": {
          "body": "Hello, Ada"
        }
      }
    }
  },
  "sessionAttributes": {},
  "promptSessionAttributes": {}
}

NewFunctionResponse returns the text verbatim. Returning an ordinary Go string instead JSON-encodes it, including string quote characters.

Read and return structured values¶

app.Tool(func(ctx context.Context, params *bedrock.Parameters, event bedrock.Event) (any, error) {
    return map[string]any{"customer": params.Get("name"), "status": "ready"}, nil
}, bedrock.Configuration{Name: "lookupCustomer"})

The TEXT body contains {"customer":"Ada","status":"ready"} for a request with name=Ada.

Manage the conversation¶

Use the event's session attributes for conversation state and FunctionResponse for custom response state. See response options for failures and reprompting.

Things to know¶

This resolver supports function-based Action Groups, not OpenAPI Action Groups.
It routes tool invocations; it does not call a foundation model.
Malformed UTF-8 in returned keys or values is an error. Return valid text rather than partially encoded bodies.

Next steps¶

See the API and behavior notes for advanced options, and module installation for dependencies.