diff --git a/aztec_macros/src/utils/ast_utils.rs b/aztec_macros/src/utils/ast_utils.rs
index 19372fa5cb5..316aa60da62 100644
--- a/aztec_macros/src/utils/ast_utils.rs
+++ b/aztec_macros/src/utils/ast_utils.rs
@@ -187,8 +187,8 @@ pub fn check_trait_method_implemented(trait_impl: &NoirTraitImpl, method_name: &
 
 /// Checks if an attribute is a custom attribute with a specific name
 pub fn is_custom_attribute(attr: &SecondaryAttribute, attribute_name: &str) -> bool {
-    if let SecondaryAttribute::Custom(custom_attr) = attr {
-        custom_attr.as_str() == attribute_name
+    if let SecondaryAttribute::Custom(custom_attribute) = attr {
+        custom_attribute.contents.as_str() == attribute_name
     } else {
         false
     }
diff --git a/compiler/noirc_driver/src/lib.rs b/compiler/noirc_driver/src/lib.rs
index 88918151366..a315e7ed397 100644
--- a/compiler/noirc_driver/src/lib.rs
+++ b/compiler/noirc_driver/src/lib.rs
@@ -452,9 +452,13 @@ fn compile_contract_inner(
             .attributes
             .secondary
             .iter()
-            .filter_map(
-                |attr| if let SecondaryAttribute::Custom(tag) = attr { Some(tag) } else { None },
-            )
+            .filter_map(|attr| {
+                if let SecondaryAttribute::Custom(attribute) = attr {
+                    Some(&attribute.contents)
+                } else {
+                    None
+                }
+            })
             .cloned()
             .collect();
 
diff --git a/compiler/noirc_errors/src/position.rs b/compiler/noirc_errors/src/position.rs
index 1792197eab7..9b031f56ae2 100644
--- a/compiler/noirc_errors/src/position.rs
+++ b/compiler/noirc_errors/src/position.rs
@@ -103,6 +103,10 @@ impl Span {
         let other_distance = other.end() - other.start();
         self_distance < other_distance
     }
+
+    pub fn shift_by(&self, offset: u32) -> Span {
+        Self::from(self.start() + offset..self.end() + offset)
+    }
 }
 
 impl From<Span> for Range<usize> {
diff --git a/compiler/noirc_frontend/src/elaborator/comptime.rs b/compiler/noirc_frontend/src/elaborator/comptime.rs
index baa9c0ab371..c28d115207d 100644
--- a/compiler/noirc_frontend/src/elaborator/comptime.rs
+++ b/compiler/noirc_frontend/src/elaborator/comptime.rs
@@ -24,7 +24,7 @@ use crate::{
     },
     node_interner::{DefinitionKind, DependencyId, FuncId, TraitId},
     parser::{self, TopLevelStatement},
-    Type, TypeBindings,
+    Type, TypeBindings, UnificationError,
 };
 
 use super::{Elaborator, FunctionContext, ResolverMeta};
@@ -96,10 +96,14 @@ impl<'context> Elaborator<'context> {
         generated_items: &mut CollectedItems,
     ) {
         for attribute in attributes {
-            if let SecondaryAttribute::Custom(name) = attribute {
-                if let Err(error) =
-                    self.run_comptime_attribute_on_item(name, item.clone(), span, generated_items)
-                {
+            if let SecondaryAttribute::Custom(attribute) = attribute {
+                if let Err(error) = self.run_comptime_attribute_on_item(
+                    &attribute.contents,
+                    item.clone(),
+                    span,
+                    attribute.contents_span,
+                    generated_items,
+                ) {
                     self.errors.push(error);
                 }
             }
@@ -111,10 +115,11 @@ impl<'context> Elaborator<'context> {
         attribute: &str,
         item: Value,
         span: Span,
+        attribute_span: Span,
         generated_items: &mut CollectedItems,
     ) -> Result<(), (CompilationError, FileId)> {
-        let location = Location::new(span, self.file);
-        let Some((function, arguments)) = Self::parse_attribute(attribute, self.file)? else {
+        let location = Location::new(attribute_span, self.file);
+        let Some((function, arguments)) = Self::parse_attribute(attribute, location)? else {
             // Do not issue an error if the attribute is unknown
             return Ok(());
         };
@@ -141,12 +146,17 @@ impl<'context> Elaborator<'context> {
         };
 
         let mut interpreter = self.setup_interpreter();
-        let mut arguments =
-            Self::handle_attribute_arguments(&mut interpreter, function, arguments, location)
-                .map_err(|error| {
-                    let file = error.get_location().file;
-                    (error.into(), file)
-                })?;
+        let mut arguments = Self::handle_attribute_arguments(
+            &mut interpreter,
+            &item,
+            function,
+            arguments,
+            location,
+        )
+        .map_err(|error| {
+            let file = error.get_location().file;
+            (error.into(), file)
+        })?;
 
         arguments.insert(0, (item, location));
 
@@ -170,33 +180,62 @@ impl<'context> Elaborator<'context> {
     #[allow(clippy::type_complexity)]
     pub(crate) fn parse_attribute(
         annotation: &str,
-        file: FileId,
+        location: Location,
     ) -> Result<Option<(Expression, Vec<Expression>)>, (CompilationError, FileId)> {
         let (tokens, mut lexing_errors) = Lexer::lex(annotation);
         if !lexing_errors.is_empty() {
-            return Err((lexing_errors.swap_remove(0).into(), file));
+            return Err((lexing_errors.swap_remove(0).into(), location.file));
         }
 
         let expression = parser::expression()
             .parse(tokens)
-            .map_err(|mut errors| (errors.swap_remove(0).into(), file))?;
+            .map_err(|mut errors| (errors.swap_remove(0).into(), location.file))?;
 
-        Ok(match expression.kind {
-            ExpressionKind::Call(call) => Some((*call.func, call.arguments)),
-            ExpressionKind::Variable(_) => Some((expression, Vec::new())),
-            _ => None,
-        })
+        let (mut func, mut arguments) = match expression.kind {
+            ExpressionKind::Call(call) => (*call.func, call.arguments),
+            ExpressionKind::Variable(_) => (expression, Vec::new()),
+            _ => return Ok(None),
+        };
+
+        func.span = func.span.shift_by(location.span.start());
+
+        for argument in &mut arguments {
+            argument.span = argument.span.shift_by(location.span.start());
+        }
+
+        Ok(Some((func, arguments)))
     }
 
     fn handle_attribute_arguments(
         interpreter: &mut Interpreter,
+        item: &Value,
         function: FuncId,
         arguments: Vec<Expression>,
         location: Location,
     ) -> Result<Vec<(Value, Location)>, InterpreterError> {
         let meta = interpreter.elaborator.interner.function_meta(&function);
+
         let mut parameters = vecmap(&meta.parameters.0, |(_, typ, _)| typ.clone());
 
+        if parameters.is_empty() {
+            return Err(InterpreterError::ArgumentCountMismatch {
+                expected: 0,
+                actual: arguments.len() + 1,
+                location,
+            });
+        }
+
+        let expected_type = item.get_type();
+        let expected_type = expected_type.as_ref();
+
+        if &parameters[0] != expected_type {
+            return Err(InterpreterError::TypeMismatch {
+                expected: parameters[0].clone(),
+                actual: expected_type.clone(),
+                location,
+            });
+        }
+
         // Remove the initial parameter for the comptime item since that is not included
         // in `arguments` at this point.
         parameters.remove(0);
@@ -213,6 +252,7 @@ impl<'context> Elaborator<'context> {
         let mut varargs = im::Vector::new();
 
         for (i, arg) in arguments.into_iter().enumerate() {
+            let arg_location = Location::new(arg.span, location.file);
             let param_type = parameters.get(i).or(varargs_elem_type).unwrap_or(&Type::Error);
 
             let mut push_arg = |arg| {
@@ -233,9 +273,17 @@ impl<'context> Elaborator<'context> {
                 }?;
                 push_arg(Value::TraitDefinition(trait_id));
             } else {
-                let expr_id = interpreter.elaborator.elaborate_expression(arg).0;
+                let (expr_id, expr_type) = interpreter.elaborator.elaborate_expression(arg);
                 push_arg(interpreter.evaluate(expr_id)?);
-            }
+
+                if let Err(UnificationError) = expr_type.unify(param_type) {
+                    return Err(InterpreterError::TypeMismatch {
+                        expected: param_type.clone(),
+                        actual: expr_type,
+                        location: arg_location,
+                    });
+                }
+            };
         }
 
         if is_varargs {
diff --git a/compiler/noirc_frontend/src/elaborator/mod.rs b/compiler/noirc_frontend/src/elaborator/mod.rs
index e84ed76050d..44240b72af0 100644
--- a/compiler/noirc_frontend/src/elaborator/mod.rs
+++ b/compiler/noirc_frontend/src/elaborator/mod.rs
@@ -28,6 +28,7 @@ use crate::{
     node_interner::{
         DefinitionKind, DependencyId, ExprId, FuncId, GlobalId, ReferenceId, TraitId, TypeAliasId,
     },
+    token::CustomAtrribute,
     Shared, Type, TypeVariable,
 };
 use crate::{
@@ -819,7 +820,7 @@ impl<'context> Elaborator<'context> {
         let attributes = func.secondary_attributes().iter();
         let attributes =
             attributes.filter_map(|secondary_attribute| secondary_attribute.as_custom());
-        let attributes = attributes.map(|str| str.to_string()).collect();
+        let attributes: Vec<CustomAtrribute> = attributes.cloned().collect();
 
         let meta = FuncMeta {
             name: name_ident,
diff --git a/compiler/noirc_frontend/src/elaborator/types.rs b/compiler/noirc_frontend/src/elaborator/types.rs
index e41234a5be5..8dccd5f0344 100644
--- a/compiler/noirc_frontend/src/elaborator/types.rs
+++ b/compiler/noirc_frontend/src/elaborator/types.rs
@@ -36,7 +36,7 @@ use crate::{
         TraitImplKind, TraitMethodId,
     },
     Generics, Kind, ResolvedGeneric, Type, TypeBinding, TypeBindings, TypeVariable,
-    TypeVariableKind,
+    TypeVariableKind, UnificationError,
 };
 
 use super::{lints, Elaborator};
@@ -713,9 +713,9 @@ impl<'context> Elaborator<'context> {
         expected: &Type,
         make_error: impl FnOnce() -> TypeCheckError,
     ) {
-        let mut errors = Vec::new();
-        actual.unify(expected, &mut errors, make_error);
-        self.errors.extend(errors.into_iter().map(|error| (error.into(), self.file)));
+        if let Err(UnificationError) = actual.unify(expected) {
+            self.errors.push((make_error().into(), self.file));
+        }
     }
 
     /// Wrapper of Type::unify_with_coercions using self.errors
diff --git a/compiler/noirc_frontend/src/hir/comptime/interpreter/builtin.rs b/compiler/noirc_frontend/src/hir/comptime/interpreter/builtin.rs
index 070749e45ba..36e6fd014d5 100644
--- a/compiler/noirc_frontend/src/hir/comptime/interpreter/builtin.rs
+++ b/compiler/noirc_frontend/src/hir/comptime/interpreter/builtin.rs
@@ -1609,7 +1609,7 @@ fn function_def_has_named_attribute(
     let name = name.iter().map(|token| token.to_string()).collect::<Vec<_>>().join("");
 
     for attribute in attributes {
-        let parse_result = Elaborator::parse_attribute(attribute, location.file);
+        let parse_result = Elaborator::parse_attribute(&attribute.contents, location);
         let Ok(Some((function, _arguments))) = parse_result else {
             continue;
         };
diff --git a/compiler/noirc_frontend/src/hir_def/function.rs b/compiler/noirc_frontend/src/hir_def/function.rs
index 7fa33746f31..8e3baef1d00 100644
--- a/compiler/noirc_frontend/src/hir_def/function.rs
+++ b/compiler/noirc_frontend/src/hir_def/function.rs
@@ -10,6 +10,7 @@ use crate::graph::CrateId;
 use crate::hir::def_map::LocalModuleId;
 use crate::macros_api::{BlockExpression, StructId};
 use crate::node_interner::{ExprId, NodeInterner, TraitId, TraitImplId};
+use crate::token::CustomAtrribute;
 use crate::{ResolvedGeneric, Type};
 
 /// A Hir function is a block expression with a list of statements.
@@ -166,7 +167,7 @@ pub struct FuncMeta {
     pub self_type: Option<Type>,
 
     /// Custom attributes attached to this function.
-    pub custom_attributes: Vec<String>,
+    pub custom_attributes: Vec<CustomAtrribute>,
 }
 
 #[derive(Debug, Clone)]
diff --git a/compiler/noirc_frontend/src/hir_def/types.rs b/compiler/noirc_frontend/src/hir_def/types.rs
index 638003d3fcd..7b3d0d7a205 100644
--- a/compiler/noirc_frontend/src/hir_def/types.rs
+++ b/compiler/noirc_frontend/src/hir_def/types.rs
@@ -1467,21 +1467,13 @@ impl Type {
     /// equal to the other type in the process. When comparing types, unification
     /// (including try_unify) are almost always preferred over Type::eq as unification
     /// will correctly handle generic types.
-    pub fn unify(
-        &self,
-        expected: &Type,
-        errors: &mut Vec<TypeCheckError>,
-        make_error: impl FnOnce() -> TypeCheckError,
-    ) {
+    pub fn unify(&self, expected: &Type) -> Result<(), UnificationError> {
         let mut bindings = TypeBindings::new();
 
-        match self.try_unify(expected, &mut bindings) {
-            Ok(()) => {
-                // Commit any type bindings on success
-                Self::apply_type_bindings(bindings);
-            }
-            Err(UnificationError) => errors.push(make_error()),
-        }
+        self.try_unify(expected, &mut bindings).map(|()| {
+            // Commit any type bindings on success
+            Self::apply_type_bindings(bindings);
+        })
     }
 
     /// `try_unify` is a bit of a misnomer since although errors are not committed,
diff --git a/compiler/noirc_frontend/src/lexer/lexer.rs b/compiler/noirc_frontend/src/lexer/lexer.rs
index 0afcb02caac..7265593238d 100644
--- a/compiler/noirc_frontend/src/lexer/lexer.rs
+++ b/compiler/noirc_frontend/src/lexer/lexer.rs
@@ -295,8 +295,12 @@ impl<'a> Lexer<'a> {
         }
         self.next_char();
 
+        let contents_start = self.position + 1;
+
         let word = self.eat_while(None, |ch| ch != ']');
 
+        let contents_end = self.position;
+
         if !self.peek_char_is(']') {
             return Err(LexerErrorKind::UnexpectedCharacter {
                 span: Span::single_char(self.position),
@@ -308,7 +312,10 @@ impl<'a> Lexer<'a> {
 
         let end = self.position;
 
-        let attribute = Attribute::lookup_attribute(&word, Span::inclusive(start, end))?;
+        let span = Span::inclusive(start, end);
+        let contents_span = Span::inclusive(contents_start, contents_end);
+
+        let attribute = Attribute::lookup_attribute(&word, span, contents_span)?;
 
         Ok(attribute.into_span(start, end))
     }
@@ -682,7 +689,7 @@ mod tests {
     use iter_extended::vecmap;
 
     use super::*;
-    use crate::token::{FunctionAttribute, SecondaryAttribute, TestScope};
+    use crate::token::{CustomAtrribute, FunctionAttribute, SecondaryAttribute, TestScope};
 
     #[test]
     fn test_single_double_char() {
@@ -810,9 +817,11 @@ mod tests {
         let token = lexer.next_token().unwrap();
         assert_eq!(
             token.token(),
-            &Token::Attribute(Attribute::Secondary(SecondaryAttribute::Custom(
-                "custom(hello)".to_string()
-            )))
+            &Token::Attribute(Attribute::Secondary(SecondaryAttribute::Custom(CustomAtrribute {
+                contents: "custom(hello)".to_string(),
+                span: Span::from(0..16),
+                contents_span: Span::from(2..15)
+            })))
         );
     }
 
diff --git a/compiler/noirc_frontend/src/lexer/token.rs b/compiler/noirc_frontend/src/lexer/token.rs
index 585e22ce92b..1692908187e 100644
--- a/compiler/noirc_frontend/src/lexer/token.rs
+++ b/compiler/noirc_frontend/src/lexer/token.rs
@@ -697,7 +697,11 @@ impl fmt::Display for Attribute {
 impl Attribute {
     /// If the string is a fixed attribute return that, else
     /// return the custom attribute
-    pub(crate) fn lookup_attribute(word: &str, span: Span) -> Result<Token, LexerErrorKind> {
+    pub(crate) fn lookup_attribute(
+        word: &str,
+        span: Span,
+        contents_span: Span,
+    ) -> Result<Token, LexerErrorKind> {
         let word_segments: Vec<&str> = word
             .split(|c| c == '(' || c == ')')
             .filter(|string_segment| !string_segment.is_empty())
@@ -770,7 +774,11 @@ impl Attribute {
             ["varargs"] => Attribute::Secondary(SecondaryAttribute::Varargs),
             tokens => {
                 tokens.iter().try_for_each(|token| validate(token))?;
-                Attribute::Secondary(SecondaryAttribute::Custom(word.to_owned()))
+                Attribute::Secondary(SecondaryAttribute::Custom(CustomAtrribute {
+                    contents: word.to_owned(),
+                    span,
+                    contents_span,
+                }))
             }
         };
 
@@ -863,17 +871,26 @@ pub enum SecondaryAttribute {
     ContractLibraryMethod,
     Export,
     Field(String),
-    Custom(String),
+    Custom(CustomAtrribute),
     Abi(String),
 
     /// A variable-argument comptime function.
     Varargs,
 }
 
+#[derive(PartialEq, Eq, Hash, Debug, Clone, PartialOrd, Ord)]
+pub struct CustomAtrribute {
+    pub contents: String,
+    // The span of the entire attribute, including leading `#[` and trailing `]`
+    pub span: Span,
+    // The span for the attribute contents (what's inside `#[...]`)
+    pub contents_span: Span,
+}
+
 impl SecondaryAttribute {
-    pub(crate) fn as_custom(&self) -> Option<&str> {
-        if let Self::Custom(str) = self {
-            Some(str)
+    pub(crate) fn as_custom(&self) -> Option<&CustomAtrribute> {
+        if let Self::Custom(attribute) = self {
+            Some(attribute)
         } else {
             None
         }
@@ -887,7 +904,7 @@ impl fmt::Display for SecondaryAttribute {
             SecondaryAttribute::Deprecated(Some(ref note)) => {
                 write!(f, r#"#[deprecated("{note}")]"#)
             }
-            SecondaryAttribute::Custom(ref k) => write!(f, "#[{k}]"),
+            SecondaryAttribute::Custom(ref attribute) => write!(f, "#[{}]", attribute.contents),
             SecondaryAttribute::ContractLibraryMethod => write!(f, "#[contract_library_method]"),
             SecondaryAttribute::Export => write!(f, "#[export]"),
             SecondaryAttribute::Field(ref k) => write!(f, "#[field({k})]"),
@@ -916,9 +933,8 @@ impl AsRef<str> for SecondaryAttribute {
         match self {
             SecondaryAttribute::Deprecated(Some(string)) => string,
             SecondaryAttribute::Deprecated(None) => "",
-            SecondaryAttribute::Custom(string)
-            | SecondaryAttribute::Field(string)
-            | SecondaryAttribute::Abi(string) => string,
+            SecondaryAttribute::Custom(attribute) => &attribute.contents,
+            SecondaryAttribute::Field(string) | SecondaryAttribute::Abi(string) => string,
             SecondaryAttribute::ContractLibraryMethod => "",
             SecondaryAttribute::Export => "",
             SecondaryAttribute::Varargs => "",