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docs/docs/tools/similar_issues.md

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+## Overview
+The similar issue tool retrieves the most similar issues to the current issue.
+It can be invoked manually by commenting on any PR:
+```
+/similar_issue
+```
+For example:
+
+<kbd><img src=https://codium.ai/images/pr_agent/similar_issue_original_issue.png width="768"></kbd>
+
+<kbd><img src=https://codium.ai/images/pr_agent/similar_issue_comment.png width="768"></kbd>
+
+<kbd><img src=https://codium.ai/images/pr_agent/similar_issue.png width="768"></kbd>
+
+Note that to perform retrieval, the `similar_issue` tool indexes all the repo previous issues (once).
+
+
+**Select VectorDBs** by changing `pr_similar_issue` parameter in `configuration.toml` file 
+
+2 VectorDBs are available to switch in
+1. LanceDB
+2. Pinecone
+
+To enable usage of the '**similar issue**' tool for Pinecone, you need to set the following keys in `.secrets.toml` (or in the relevant environment variables):
+
+```
+[pinecone]
+api_key = "..."
+environment = "..."
+```
+These parameters can be obtained by registering to [Pinecone](https://app.pinecone.io/?sessionType=signup/).
+
+
+## How to use:
+- To invoke the 'similar issue' tool from **CLI**, run:
+`python3 cli.py --issue_url=... similar_issue`
+
+- To invoke the 'similar' issue tool via online usage, [comment](https://github.com/Codium-ai/pr-agent/issues/178#issuecomment-1716934893) on a PR:
+`/similar_issue`
+
+- You can also enable the 'similar issue' tool to run automatically when a new issue is opened, by adding it to the [pr_commands list in the github_app section](https://github.com/Codium-ai/pr-agent/blob/main/pr_agent/settings/configuration.toml#L66)