diff --git a/crates/aura-std/src/abs.rs b/crates/aura-std/src/abs.rs
index d57ca26..f94c6d7 100644
--- a/crates/aura-std/src/abs.rs
+++ b/crates/aura-std/src/abs.rs
@@ -23,6 +23,7 @@ impl Abs {
                 inputs: vec![PortSpec { kind: ScalarKind::F64, firing: Firing::Any, name: "value".into() }],
                 output: vec![FieldSpec { name: "value".into(), kind: ScalarKind::F64 }],
                 params: vec![],
+                doc: "absolute value of the input series",
             },
             |_| Box::new(Abs::new()),
         )
diff --git a/crates/aura-std/src/add.rs b/crates/aura-std/src/add.rs
index f8e9c49..5e355a8 100644
--- a/crates/aura-std/src/add.rs
+++ b/crates/aura-std/src/add.rs
@@ -38,6 +38,7 @@ impl Add {
                 ],
                 output: vec![FieldSpec { name: "value".into(), kind: ScalarKind::F64 }],
                 params: vec![],
+                doc: "elementwise sum of two input series",
             },
             |_| Box::new(Add::new()),
         )
diff --git a/crates/aura-std/src/and.rs b/crates/aura-std/src/and.rs
index 810606d..1aacbff 100644
--- a/crates/aura-std/src/and.rs
+++ b/crates/aura-std/src/and.rs
@@ -37,6 +37,7 @@ impl And {
                 ],
                 output: vec![FieldSpec { name: "value".into(), kind: ScalarKind::Bool }],
                 params: vec![],
+                doc: "logical AND of two boolean series",
             },
             |_| Box::new(And::new()),
         )
diff --git a/crates/aura-std/src/const_node.rs b/crates/aura-std/src/const_node.rs
index 758e016..002c48a 100644
--- a/crates/aura-std/src/const_node.rs
+++ b/crates/aura-std/src/const_node.rs
@@ -33,6 +33,7 @@ impl Const {
                 inputs: vec![PortSpec { kind: ScalarKind::F64, firing: Firing::Any, name: "clock".into() }],
                 output: vec![FieldSpec { name: "value".into(), kind: ScalarKind::F64 }],
                 params: vec![ParamSpec { name: "value".into(), kind: ScalarKind::F64 }],
+                doc: "constant-valued stream from a single param",
             },
             |p| Box::new(Const::new(p[0].f64())),
         )
diff --git a/crates/aura-std/src/cumsum.rs b/crates/aura-std/src/cumsum.rs
index df4f168..d6376b8 100644
--- a/crates/aura-std/src/cumsum.rs
+++ b/crates/aura-std/src/cumsum.rs
@@ -53,6 +53,7 @@ impl CumSum {
                 inputs: vec![PortSpec { kind: ScalarKind::F64, firing: Firing::Any, name: "series".into() }],
                 output: vec![FieldSpec { name: "value".into(), kind: ScalarKind::F64 }],
                 params: vec![],
+                doc: "running cumulative sum of the input series",
             },
             |_| Box::new(CumSum::new()),
         )
diff --git a/crates/aura-std/src/delay.rs b/crates/aura-std/src/delay.rs
index 164c5ae..180ebc8 100644
--- a/crates/aura-std/src/delay.rs
+++ b/crates/aura-std/src/delay.rs
@@ -65,6 +65,7 @@ impl Delay {
                 inputs: vec![PortSpec { kind: ScalarKind::F64, firing: Firing::Any, name: "series".into() }],
                 output: vec![FieldSpec { name: "value".into(), kind: ScalarKind::F64 }],
                 params: vec![ParamSpec { name: "lag".into(), kind: ScalarKind::I64 }],
+                doc: "emits the input from `lag` cycles ago — the explicit delay register (C5)",
             },
             |p| Box::new(Delay::new(p[0].i64() as usize)),
         )
diff --git a/crates/aura-std/src/div.rs b/crates/aura-std/src/div.rs
index 9187641..97ef6b1 100644
--- a/crates/aura-std/src/div.rs
+++ b/crates/aura-std/src/div.rs
@@ -30,6 +30,7 @@ impl Div {
                 ],
                 output: vec![FieldSpec { name: "value".into(), kind: ScalarKind::F64 }],
                 params: vec![],
+                doc: "elementwise quotient of two input series",
             },
             |_| Box::new(Div::new()),
         )
diff --git a/crates/aura-std/src/ema.rs b/crates/aura-std/src/ema.rs
index a112a86..f0a3770 100644
--- a/crates/aura-std/src/ema.rs
+++ b/crates/aura-std/src/ema.rs
@@ -63,6 +63,7 @@ impl Ema {
                 inputs: vec![PortSpec { kind: ScalarKind::F64, firing: Firing::Any, name: "series".into() }],
                 output: vec![FieldSpec { name: "value".into(), kind: ScalarKind::F64 }],
                 params: vec![ParamSpec { name: "length".into(), kind: ScalarKind::I64 }],
+                doc: "exponential moving average over the input series",
             },
             |p| Box::new(Ema::new(p[0].i64() as usize)),
         )
diff --git a/crates/aura-std/src/eqconst.rs b/crates/aura-std/src/eqconst.rs
index d6a638d..e9ed44e 100644
--- a/crates/aura-std/src/eqconst.rs
+++ b/crates/aura-std/src/eqconst.rs
@@ -40,6 +40,7 @@ impl EqConst {
                 inputs: vec![PortSpec { kind: ScalarKind::I64, firing: Firing::Any, name: "value".into() }],
                 output: vec![FieldSpec { name: "value".into(), kind: ScalarKind::Bool }],
                 params: vec![ParamSpec { name: "target".into(), kind: ScalarKind::I64 }],
+                doc: "true where the input equals a constant param",
             },
             |p| Box::new(EqConst::new(p[0].i64())),
         )
diff --git a/crates/aura-std/src/gated_recorder.rs b/crates/aura-std/src/gated_recorder.rs
index 943a799..92e2d96 100644
--- a/crates/aura-std/src/gated_recorder.rs
+++ b/crates/aura-std/src/gated_recorder.rs
@@ -41,7 +41,12 @@ impl GatedRecorder {
         let build_kinds = kinds.clone();
         PrimitiveBuilder::new(
             "GatedRecorder",
-            NodeSchema { inputs, output: vec![], params: vec![] }, // sink: empty output (C8)
+            NodeSchema {
+                inputs,
+                output: vec![],
+                params: vec![],
+                doc: "recording sink that persists its input while the gate is true, plus a final row at finalize",
+            }, // sink: empty output (C8)
             move |_| Box::new(GatedRecorder::new(&build_kinds, gate_col, tx.clone())),
         )
     }
diff --git a/crates/aura-std/src/gt.rs b/crates/aura-std/src/gt.rs
index de4fc1a..de0e2db 100644
--- a/crates/aura-std/src/gt.rs
+++ b/crates/aura-std/src/gt.rs
@@ -39,6 +39,7 @@ impl Gt {
                 ],
                 output: vec![FieldSpec { name: "value".into(), kind: ScalarKind::Bool }],
                 params: vec![],
+                doc: "true where the first input exceeds the second",
             },
             |_| Box::new(Gt::new()),
         )
diff --git a/crates/aura-std/src/latch.rs b/crates/aura-std/src/latch.rs
index ad4747e..b9098e8 100644
--- a/crates/aura-std/src/latch.rs
+++ b/crates/aura-std/src/latch.rs
@@ -46,6 +46,7 @@ impl Latch {
                 ],
                 output: vec![FieldSpec { name: "value".into(), kind: ScalarKind::F64 }],
                 params: vec![],
+                doc: "level-sensitive set/reset register holding 1.0 when latched, 0.0 when reset",
             },
             |_| Box::new(Latch::new()),
         )
diff --git a/crates/aura-std/src/lincomb.rs b/crates/aura-std/src/lincomb.rs
index 22e3884..b02c899 100644
--- a/crates/aura-std/src/lincomb.rs
+++ b/crates/aura-std/src/lincomb.rs
@@ -52,7 +52,12 @@ impl LinComb {
             .collect();
         PrimitiveBuilder::new(
             "LinComb",
-            NodeSchema { inputs, output: vec![FieldSpec { name: "value".into(), kind: ScalarKind::F64 }], params },
+            NodeSchema {
+                inputs,
+                output: vec![FieldSpec { name: "value".into(), kind: ScalarKind::F64 }],
+                params,
+                doc: "linear combination of its inputs with constant weights",
+            },
             |p| Box::new(LinComb::new(
                 p.iter().map(|c| c.f64()).collect(),
             )),
diff --git a/crates/aura-std/src/max.rs b/crates/aura-std/src/max.rs
index 6f67ab5..1056d9b 100644
--- a/crates/aura-std/src/max.rs
+++ b/crates/aura-std/src/max.rs
@@ -26,6 +26,7 @@ impl Max {
                 ],
                 output: vec![FieldSpec { name: "value".into(), kind: ScalarKind::F64 }],
                 params: vec![],
+                doc: "elementwise maximum of two input series",
             },
             |_| Box::new(Max::new()),
         )
diff --git a/crates/aura-std/src/min.rs b/crates/aura-std/src/min.rs
index e37ae19..2a3d9cc 100644
--- a/crates/aura-std/src/min.rs
+++ b/crates/aura-std/src/min.rs
@@ -27,6 +27,7 @@ impl Min {
                 ],
                 output: vec![FieldSpec { name: "value".into(), kind: ScalarKind::F64 }],
                 params: vec![],
+                doc: "elementwise minimum of two input series",
             },
             |_| Box::new(Min::new()),
         )
diff --git a/crates/aura-std/src/mul.rs b/crates/aura-std/src/mul.rs
index cac49a2..137431b 100644
--- a/crates/aura-std/src/mul.rs
+++ b/crates/aura-std/src/mul.rs
@@ -24,6 +24,7 @@ impl Mul {
                 ],
                 output: vec![FieldSpec { name: "value".into(), kind: ScalarKind::F64 }],
                 params: vec![],
+                doc: "elementwise product of two input series",
             },
             |_| Box::new(Mul::new()),
         )
diff --git a/crates/aura-std/src/recorder.rs b/crates/aura-std/src/recorder.rs
index 796b1c2..063bb8a 100644
--- a/crates/aura-std/src/recorder.rs
+++ b/crates/aura-std/src/recorder.rs
@@ -53,7 +53,12 @@ impl Recorder {
         let build_kinds = kinds.clone();
         PrimitiveBuilder::new(
             "Recorder",
-            NodeSchema { inputs, output: vec![], params: vec![] }, // sink: empty output (C8)
+            NodeSchema {
+                inputs,
+                output: vec![],
+                params: vec![],
+                doc: "recording sink persisting its input series into the trace store",
+            }, // sink: empty output (C8)
             move |_| Box::new(Recorder::new(&build_kinds, firing, tx.clone())),
         )
     }
diff --git a/crates/aura-std/src/rolling_max.rs b/crates/aura-std/src/rolling_max.rs
index 8149031..cc1af67 100644
--- a/crates/aura-std/src/rolling_max.rs
+++ b/crates/aura-std/src/rolling_max.rs
@@ -54,6 +54,7 @@ impl RollingMax {
                 inputs: vec![PortSpec { kind: ScalarKind::F64, firing: Firing::Any, name: "series".into() }],
                 output: vec![FieldSpec { name: "value".into(), kind: ScalarKind::F64 }],
                 params: vec![ParamSpec { name: "length".into(), kind: ScalarKind::I64 }],
+                doc: "rolling maximum over a fixed lookback window",
             },
             |p| Box::new(RollingMax::new(p[0].i64() as usize)),
         )
diff --git a/crates/aura-std/src/rolling_min.rs b/crates/aura-std/src/rolling_min.rs
index 2ff15d5..4f7d705 100644
--- a/crates/aura-std/src/rolling_min.rs
+++ b/crates/aura-std/src/rolling_min.rs
@@ -43,6 +43,7 @@ impl RollingMin {
                 inputs: vec![PortSpec { kind: ScalarKind::F64, firing: Firing::Any, name: "series".into() }],
                 output: vec![FieldSpec { name: "value".into(), kind: ScalarKind::F64 }],
                 params: vec![ParamSpec { name: "length".into(), kind: ScalarKind::I64 }],
+                doc: "rolling minimum over a fixed lookback window",
             },
             |p| Box::new(RollingMin::new(p[0].i64() as usize)),
         )
diff --git a/crates/aura-std/src/scale.rs b/crates/aura-std/src/scale.rs
index a1e4d66..d2aa90d 100644
--- a/crates/aura-std/src/scale.rs
+++ b/crates/aura-std/src/scale.rs
@@ -28,6 +28,7 @@ impl Scale {
                 inputs: vec![PortSpec { kind: ScalarKind::F64, firing: Firing::Any, name: "signal".into() }],
                 output: vec![FieldSpec { name: "value".into(), kind: ScalarKind::F64 }],
                 params: vec![ParamSpec { name: "factor".into(), kind: ScalarKind::F64 }],
+                doc: "input multiplied by a constant factor param",
             },
             |p| Box::new(Scale::new(p[0].f64())),
         )
diff --git a/crates/aura-std/src/select.rs b/crates/aura-std/src/select.rs
index 81c7e41..1a09fca 100644
--- a/crates/aura-std/src/select.rs
+++ b/crates/aura-std/src/select.rs
@@ -38,6 +38,7 @@ impl Select {
                 ],
                 output: vec![FieldSpec { name: "value".into(), kind: ScalarKind::F64 }],
                 params: vec![],
+                doc: "chooses between two inputs by a boolean selector",
             },
             |_| Box::new(Select::new()),
         )
diff --git a/crates/aura-std/src/series_reducer.rs b/crates/aura-std/src/series_reducer.rs
index 83099a8..fa7630a 100644
--- a/crates/aura-std/src/series_reducer.rs
+++ b/crates/aura-std/src/series_reducer.rs
@@ -26,6 +26,7 @@ impl SeriesReducer {
                 inputs: vec![PortSpec { kind: ScalarKind::F64, firing, name: "col[0]".to_string() }],
                 output: vec![], // sink: empty output (C8)
                 params: vec![],
+                doc: "folds an input series into a single summary row emitted at finalize",
             },
             move |_| Box::new(SeriesReducer::new(tx.clone())),
         )
diff --git a/crates/aura-std/src/sign.rs b/crates/aura-std/src/sign.rs
index ca0a816..0cd1384 100644
--- a/crates/aura-std/src/sign.rs
+++ b/crates/aura-std/src/sign.rs
@@ -36,6 +36,7 @@ impl Sign {
                 inputs: vec![PortSpec { kind: ScalarKind::F64, firing: Firing::Any, name: "value".into() }],
                 output: vec![FieldSpec { name: "value".into(), kind: ScalarKind::F64 }],
                 params: vec![],
+                doc: "sign of the input: -1, 0 or +1",
             },
             |_| Box::new(Sign::new()),
         )
diff --git a/crates/aura-std/src/sma.rs b/crates/aura-std/src/sma.rs
index 2e9c97d..d30c743 100644
--- a/crates/aura-std/src/sma.rs
+++ b/crates/aura-std/src/sma.rs
@@ -65,6 +65,7 @@ impl Sma {
                 inputs: vec![PortSpec { kind: ScalarKind::F64, firing: Firing::Any, name: "series".into() }],
                 output: vec![FieldSpec { name: "value".into(), kind: ScalarKind::F64 }],
                 params: vec![ParamSpec { name: "length".into(), kind: ScalarKind::I64 }],
+                doc: "simple moving average over the input series",
             },
             |p| Box::new(Sma::new(p[0].i64() as usize)),
         )
diff --git a/crates/aura-std/src/sqrt.rs b/crates/aura-std/src/sqrt.rs
index bec11fd..9d819c5 100644
--- a/crates/aura-std/src/sqrt.rs
+++ b/crates/aura-std/src/sqrt.rs
@@ -23,6 +23,7 @@ impl Sqrt {
                 inputs: vec![PortSpec { kind: ScalarKind::F64, firing: Firing::Any, name: "value".into() }],
                 output: vec![FieldSpec { name: "value".into(), kind: ScalarKind::F64 }],
                 params: vec![],
+                doc: "square root of the input series",
             },
             |_| Box::new(Sqrt::new()),
         )
diff --git a/crates/aura-std/src/sub.rs b/crates/aura-std/src/sub.rs
index 72254b6..4d651f9 100644
--- a/crates/aura-std/src/sub.rs
+++ b/crates/aura-std/src/sub.rs
@@ -29,6 +29,7 @@ impl Sub {
                 ],
                 output: vec![FieldSpec { name: "value".into(), kind: ScalarKind::F64 }],
                 params: vec![],
+                doc: "elementwise difference of two input series",
             },
             |_| Box::new(Sub::new()),
         )
diff --git a/crates/aura-std/src/when.rs b/crates/aura-std/src/when.rs
index 6f3ca56..bb22c49 100644
--- a/crates/aura-std/src/when.rs
+++ b/crates/aura-std/src/when.rs
@@ -46,6 +46,7 @@ impl When {
                 ],
                 output: vec![FieldSpec { name: "value".into(), kind: ScalarKind::F64 }],
                 params: vec![],
+                doc: "emits the input only on cycles where the condition input is true",
             },
             |_| Box::new(When::new()),
         )