diff --git a/README.md b/README.md
index db796ed..0f1b2a9 100644
--- a/README.md
+++ b/README.md
@@ -1,27 +1,41 @@
 swh-mirror-forge
 ================
 
 Mirror swh's forge to github
 
 # Configuration
 
-In $SWH_CONFIG_PATH/mirror-forge/config.yml (SWH_CONFIG_PATH being one
-of /etc/softwareheritage/,~/.config/swh, or ~/.swh/), add the
-following information:
+In $SWH_CONFIG_PATH/mirror-forge/config.yml (SWH_CONFIG_PATH being in
+{/etc/softwareheritage/,~/.config/swh, ~/.swh/}), add the following
+information:
 
 ```yaml
 github: <github-api-token>
 forge: <forge-api-token>
 ```
 
 Docs:
 - github: https://github.com/settings/tokens
 - swh forge: https://forge.softwareheritage.org/settings/user/<your-user>/page/apitokens/
 
 # Use
 
 For now, on a per repository basis:
 
 ```sh
 python3 -m swh.mirror.forge.sync --repo-callsign DMOD --credential-key-id 3
 ```
+
+# What does this do?
+
+- Retrieve information on the repository identified by the callsign
+  provided as parameter (--repo-callsign).
+
+- Determine the repository's name, repository's forge's url,
+  repository's description
+
+- Create an empty repository in github with the same name, description
+  and pointing back to the origin fork using the phabricator url
+
+- Associate the github uri in the phabricator forge as a mirror. This
+  uses the credential key information provided as parameter (--credential-key)