feat: search index tool

[yuye-aws]

Description

Implement SearchIndexTool to support agent framework. It takes in two string parameters: index and query. Here is the sample usage of this tool. Please remember to replace the model id and agent id.

POST /_plugins/_ml/agents/_register
{
  "name": "Test_Agent_For_ReAct",
  "type": "conversational",
  "description": "this is a test agent",
  "llm": {
    "model_id": "xxxxx",
    "parameters": {
      "max_iteration": 10,
      "stop_when_no_tool_found": true,
      "response_filter": "$.completion"
    }
  },
  "memory": {
    "type": "conversation_index"
  },
  "tools": [
    {
      "type": "SearchIndexTool",
      "description": "Use this tool to search index with a query. You should pass in two parameters: index and query. Index is the index name and the query is an OpenSearch DSL query."
    }
  ],
  "app_type": "my app"
}


POST /_plugins/_ml/agents/xxxxx/_execute
{
  "parameters": {
    "question": "Show me all the name field of all documents in index .plugins-ml-agent",
    "verbose": true
  }
}

The expected successful response should be

{
  "inference_results": [
    {
      "output": [
        {
          "name": "memory_id",
          "result": "xxxxx"
        },
        {
          "name": "response",
          "result": "Thought: To get the name field of documents in the .plugins-ml-agent index, I should search that index using the SearchIndexTool."
        },
        {
          "name": "response",
          "result": "\nObservation: \"{\\\"_index\\\":\\\".plugins-ml-agent\\\",\\\"_source\\\":{\\\"name\\\":\\\"Test_Agent_For_ReAct\\\"},\\\"_id\\\":\\\"xxxxx\\\",\\\"_score\\\":1.0}\\n\""
        },
        {
          "name": "response",
          "result": "Based on the information I was previously provided from searching the index, the name field of the documents in the .plugins-ml-agent index contains 'Test_Agent_For_ReAct'."
        },
        {
          "name": "response",
          "result": "The name field of the documents in the .plugins-ml-agent index is 'Test_Agent_For_ReAct'."
        }
      ]
    }
  ]
}

If there is error when parsing the input, the expected error response could be:

{
  "error": {
    "root_cause": [
      {
        "type": "illegal_argument_exception",
        "reason": "[query] is null or empty, can not process it."
      }
    ],
    "type": "illegal_argument_exception",
    "reason": "[query] is null or empty, can not process it."
  },
  "status": 400
}

Issues Resolved

1. Implement search index tool
2. Fix bugs in unit tests

Check List

• New functionality includes testing.
  • All tests pass
• New functionality has been documented.
  • New functionality has javadoc added
• Commits are signed per the DCO using --signoff

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[codecov]

Codecov Report

Attention: 18 lines in your changes are missing coverage. Please review.

Comparison is base (37bbd3b) 46.08% compared to head (724c33a) 80.38%.
Report is 2 commits behind head on main.

Files	Patch %	Lines
...va/org/opensearch/agent/tools/SearchIndexTool.java	72.58%	12 Missing and 5 partials ⚠️
src/main/java/org/opensearch/agent/ToolPlugin.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##               main      #61       +/-   ##
=============================================
+ Coverage     46.08%   80.38%   +34.29%     
- Complexity       31       90       +59     
=============================================
  Files             6        8        +2     
  Lines           358      520      +162     
  Branches         42       70       +28     
=============================================
+ Hits            165      418      +253     
+ Misses          172       58      -114     
- Partials         21       44       +23     

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[zane-neo]

Please check the codecov report and add more UTs.

[xinyual]

Why we need a toJson here after calling toString?

[yuye-aws]

Sorry, there is no need for toJson. Thanks for pointing out.

[yuye-aws]

Please check the codecov report and add more UTs.

I have added UT to cover more code. This PR is ready for review now.

[dhrubo-os]

how about : Use this tool to search an index by providing two parameters: 'index' for the index name, and 'query' for the OpenSearch DSL formatted query.