diff --git a/src/commands/index.js b/src/commands/index.js
index c80a590..dc615d6 100644
--- a/src/commands/index.js
+++ b/src/commands/index.js
@@ -12,36 +12,44 @@ module.exports = [
     topic: 'data.clock',
     aliases: ['clock'],
     payloadSchema: { type: 'any' },
+    description: 'Push the simulation clock tick (timestamp / dt) to the ASM solver.',
     handler: handlers.dataClock,
   },
   {
     topic: 'data.fluent',
     aliases: ['Fluent'],
     payloadSchema: { type: 'object' },
+    // Compound payload `{F, C: [...]}` — registry-level units normalisation is
+    // skipped (the handler converts per-field internally).
+    description: 'Push the influent stream (payload: {F: flow m3/h, C: [concentrations mg/L]}).',
     handler: handlers.dataFluent,
   },
   {
     topic: 'data.otr',
     aliases: ['OTR'],
     payloadSchema: { type: 'any' },
+    description: 'Push the current oxygen-transfer rate into the reactor.',
     handler: handlers.dataOTR,
   },
   {
     topic: 'data.temperature',
     aliases: ['Temperature'],
     payloadSchema: { type: 'any' },
+    description: 'Push the current reactor temperature.',
     handler: handlers.dataTemperature,
   },
   {
     topic: 'data.dispersion',
     aliases: ['Dispersion'],
     payloadSchema: { type: 'any' },
+    description: 'Push a dispersion/mixing parameter update.',
     handler: handlers.dataDispersion,
   },
   {
     topic: 'child.register',
     aliases: ['registerChild'],
     payloadSchema: { type: 'any' },
+    description: 'Register a child node (settler / measurement) with this reactor.',
     handler: handlers.childRegister,
   },
 ];