docs: update custom labels configuration and usage instructions in describe tool

docs/docs/tools/describe.md

@@ -150,30 +150,33 @@ The marker `pr_agent:type` will be replaced with the PR type, `pr_agent:summary`
 - `include_generated_by_header`: if set to true, the tool will add a dedicated header: 'Generated by PR Agent at ...' to any automatic content. Default is true.
 
 ## Custom labels
-
 The default labels of the describe tool are quite generic, since they are meant to be used in any repo: [`Bug fix`, `Tests`, `Enhancement`, `Documentation`, `Other`].
 
 You can define custom labels that are relevant for your repo and use cases.
 Custom labels can be defined in a [configuration file](https://pr-agent-docs.codium.ai/tools/custom_labels/#configuration-options), or directly in the repo's [labels page](#handle-custom-labels-from-the-repos-labels-page).
 
-Examples for custom labels:
-
-  - `Main topic:performance` -  pr_agent:The main topic of this PR is performance
-  - `New endpoint` -  pr_agent:A new endpoint was added in this PR
-  - `SQL query` -  pr_agent:A new SQL query was added in this PR
-  - `Dockerfile changes` - pr_agent:The PR contains changes in the Dockerfile
-  - ...
-
-The list above is eclectic, and aims to give an idea of different possibilities. Define custom labels that are relevant for your repo and use cases.
-Note that Labels are not mutually exclusive, so you can add multiple label categories.
-<br>
 Make sure to provide proper title, and a detailed and well-phrased description for each label, so the tool will know when to suggest it.
 Each label description should be a **conditional statement**, that indicates if to add the label to the PR or not, according to the PR content.
 
+### Handle custom labels from a configuration file
+Example for a custom labels configuration setup in a configuration file:
+```
+[config]
+enable_custom_labels=true
+
+
+[custom_labels."sql_changes"]
+description = "Use when a PR contains changes to SQL queries"
+
+[custom_labels."test"]
+description = "use when a PR primarily contains new tests"
+
+...
+```
 
 ### Handle custom labels from the Repo's labels page 💎
 
-You can control  the custom labels that will be suggested by the `describe` tool, from the repo's labels page:
+You can also control the custom labels that will be suggested by the `describe` tool from the repo's labels page:
 
 * GitHub : go to `https://github.com/{owner}/{repo}/labels` (or click on the "Labels" tab in the issues or PRs page)
 * GitLab : go to `https://gitlab.com/{owner}/{repo}/-/labels` (or click on "Manage" -> "Labels" on the left menu)
@@ -183,6 +186,14 @@ Now add/edit the custom labels. they should be formatted as follows:
 * Label name: The name of the custom label.
 * Description: Start the description of with prefix `pr_agent:`, for example: `pr_agent: Description of when AI should suggest this label`.<br>
 
+Examples for custom labels:
+
+  - `Main topic:performance` -  pr_agent:The main topic of this PR is performance
+  - `New endpoint` -  pr_agent:A new endpoint was added in this PR
+  - `SQL query` -  pr_agent:A new SQL query was added in this PR
+  - `Dockerfile changes` - pr_agent:The PR contains changes in the Dockerfile
+  - ...
+
 The description should be comprehensive and detailed, indicating when to add the desired label. For example:
 ![Add native custom labels](https://codium.ai/images/pr_agent/add_native_custom_labels.png){width=768}
 

pr_agent/algo/utils.py

@@ -505,7 +505,7 @@ def set_custom_labels(variables, git_provider=None):
     if not get_settings().config.enable_custom_labels:
         return
 
-    labels = get_settings().custom_labels
+    labels = get_settings().get('custom_labels', {})
     if not labels:
         # set default labels
         labels = ['Bug fix', 'Tests', 'Bug fix with tests', 'Enhancement', 'Documentation', 'Other']