add previous key for PPL tool

[xinyual]

Description

add previous key for PPL tool, so we can extract content from previous tool output.
request body would be like:

{
      "type": "CatIndexTool",
      "name": "CatIndexTool2",
      "description": "Use this tool to get OpenSearch index information: (health, status, index, uuid, primary count, replica count, docs.count, docs.deleted, store.size, primary.store.size). Also, use this to get all index name. You should always use this tool when you are asked questions about indices number."
    },
      {
      "type": "PPLTool",
      "name": "TransferQuestionToPPLAndExecuteTool",
      "description": "Use this tool to transfer natural language to generate PPL and execute PPL to query inside. Use this tool after you know the index name, otherwise, call IndexRoutingTool first. The input parameters are: {index:IndexName, question:UserQuestion}",
      "parameters": {
        "model_id": "PrlMEI0BavJyXuD79Loi",
        "model_type": "CLAUDE",
        "previous_tool_name": "CatIndexTool3",
        "response_filter": "$.completion"
      }
    }
 

The previous_tool_name should be name of previous tool

Issues Resolved

add previous key for PPL tool, so we can extract content from previous tool output.

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: 3 lines in your changes are missing coverage. Please review.

Comparison is base (940ac32) 81.75% compared to head (91fd51f) 81.76%.
Report is 1 commits behind head on main.

Files	Patch %	Lines
.../main/java/org/opensearch/agent/tools/PPLTool.java	85.71%	1 Missing and 2 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #131      +/-   ##
============================================
+ Coverage     81.75%   81.76%   +0.01%     
- Complexity      197      201       +4     
============================================
  Files            13       13              
  Lines          1003     1042      +39     
  Branches        132      139       +7     
============================================
+ Hits            820      852      +32     
- Misses          133      136       +3     
- Partials         50       54       +4     

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[Hailong-am]

should we handle 'Not sure' here ?

[xinyual]

Ok. Once the index routing pr is merged I will check whether the index is equal to NOT_SURE and then throw an exception if it is.

[zane-neo]

This should work for PPLTool case, but I'm thinking of creating a systematically approach to deal with the tool results passing through the agent execute flow, e.g. a map contains all tool's result with iteration number. That would need bigger effort but that should be the correct direction. Please evaluate the effort and better creating a design doc to involve broader audience.

[zane-neo]

please use camel naming convention for variables

[zane-neo]

This two line can be merged together

[xinyual]

Already changed

[opensearch-trigger-bot]

The backport to 2.x failed:

The process '/usr/bin/git' failed with exit code 128

To backport manually, run these commands in your terminal:

# Navigate to the root of your repository
cd $(git rev-parse --show-toplevel)
# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add ../.worktrees/skills/backport-2.x 2.x
# Navigate to the new working tree
pushd ../.worktrees/skills/backport-2.x
# Create a new branch
git switch --create backport/backport-131-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 c2a1fedd0a70959c6375a30df6e823989d74c295
# Push it to GitHub
git push --set-upstream origin backport/backport-131-to-2.x
# Go back to the original working tree
popd
# Delete the working tree
git worktree remove ../.worktrees/skills/backport-2.x

Then, create a pull request where the base branch is 2.x and the compare/head branch is backport/backport-131-to-2.x.