diff --git a/progenitor-impl/src/cli.rs b/progenitor-impl/src/cli.rs
index a5c6cee..f7d265d 100644
--- a/progenitor-impl/src/cli.rs
+++ b/progenitor-impl/src/cli.rs
@@ -196,6 +196,105 @@ impl Generator {
         &mut self,
         method: &crate::method::OperationMethod,
     ) -> CliOperation {
+        // Preprocess the body parameter (if there is one) to create an
+        // iterator of top-level properties that can be represented as scalar
+        // values. We use these to create `clap::Arg` structures and then to
+        // build up the body parameter in the actual API call.
+        let body_params = method
+            .params
+            .iter()
+            .find(|param| {
+                matches!(&param.kind, OperationParameterKind::Body(_))
+                // TODO not sure how to deal with raw bodies right now
+                    && matches!(&param.typ, OperationParameterType::Type(_))
+            })
+            .into_iter()
+            .flat_map(|param| {
+                let OperationParameterType::Type(type_id) = &param.typ else {
+                    unreachable!();
+                };
+
+                let body_arg_type = self.type_space.get_type(type_id).unwrap();
+                let details = body_arg_type.details();
+
+                match details {
+                    typify::TypeDetails::Struct(struct_info) => {
+                        struct_info
+                            .properties_info()
+                            .filter_map(|prop_info| {
+                                let TypeStructPropInfo {
+                                    name: prop_name,
+                                    description,
+                                    required,
+                                    type_id: prop_type_id,
+                                } = prop_info;
+                                let prop_type = self
+                                    .type_space
+                                    .get_type(&prop_type_id)
+                                    .unwrap();
+
+                                // TODO this is maybe a kludge--not completely sure
+                                // of the right way to handle option types. On one
+                                // hand, we could want types from this interface to
+                                // never show us Option<T> types--we could let the
+                                // `required` field give us that information. On
+                                // the other hand, there might be Option types that
+                                // are required ... at least in the JSON sense,
+                                // meaning that we need to include `"foo": null`
+                                // rather than omitting the field. Back to the
+                                // first hand: is that last point just a serde
+                                // issue rather than an interface one?
+                                let maybe_inner_type =
+                                    if let typify::TypeDetails::Option(
+                                        inner_type_id,
+                                    ) = prop_type.details()
+                                    {
+                                        let inner_type = self
+                                            .type_space
+                                            .get_type(&inner_type_id)
+                                            .unwrap();
+                                        Some(inner_type)
+                                    } else {
+                                        None
+                                    };
+
+                                let prop_type = if let Some(inner_type) =
+                                    maybe_inner_type
+                                {
+                                    inner_type
+                                } else {
+                                    prop_type
+                                };
+
+                                let prop_type_ident = prop_type.ident();
+                                let scalar =
+                                    prop_type.has_impl(TypeSpaceImpl::FromStr);
+                                let prop_name = prop_name.to_kebab_case();
+
+                                // println!(
+                                //     "{}::{}: {}; scalar: {}; required: {}",
+                                //     body_args.name(),
+                                //     prop_name,
+                                //     prop_type.name(),
+                                //     scalar,
+                                //     required,
+                                // );
+
+                                scalar.then(|| {
+                                    (
+                                        prop_name.clone(),
+                                        required,
+                                        description.map(str::to_string),
+                                        prop_type_ident.clone(),
+                                    )
+                                })
+                            })
+                            .collect::<Vec<_>>()
+                    }
+                    _ => Vec::new(),
+                }
+            })
+            .collect::<Vec<_>>();
         let fn_name = format_ident!("cli_{}", &method.operation_id);
 
         let args = method
@@ -246,109 +345,24 @@ impl Generator {
                 }
             });
 
-        let maybe_body_param = method.params.iter().find(|param| {
-            matches!(&param.kind, OperationParameterKind::Body(_))
-                // TODO not sure how to deal with raw bodies right now
-                    && matches!(&param.typ, OperationParameterType::Type(_))
-        });
-
-        let body_arg = maybe_body_param.map(|param| {
-            let OperationParameterType::Type(type_id) = &param.typ else {
-                unreachable!();
-            };
-
-            let body_args = self.type_space.get_type(type_id).unwrap();
-
-            let body_arg = match body_args.details() {
-                typify::TypeDetails::Struct(s) => {
-                    s.properties_info()
-                        .filter_map(|prop_info| {
-                            let TypeStructPropInfo {
-                                name: prop_name,
-                                description,
-                                required,
-                                type_id: prop_type_id,
-                            } = prop_info;
-                            let prop_type = self
-                                .type_space
-                                .get_type(&prop_type_id)
-                                .unwrap();
-
-                            // TODO this is maybe a kludge--not completely sure
-                            // of the right way to handle option types. On one
-                            // hand, we could want types from this interface to
-                            // never show us Option<T> types--we could let the
-                            // `required` field give us that information. On
-                            // the other hand, there might be Option types that
-                            // are required ... at least in the JSON sense,
-                            // meaning that we need to include `"foo": null`
-                            // rather than omitting the field. Back to the
-                            // first hand: is that last point just a serde
-                            // issue rather than an interface one?
-                            let maybe_inner_type =
-                                if let typify::TypeDetails::Option(
-                                    inner_type_id,
-                                ) = prop_type.details()
-                                {
-                                    let inner_type = self
-                                        .type_space
-                                        .get_type(&inner_type_id)
-                                        .unwrap();
-                                    Some(inner_type)
-                                } else {
-                                    None
-                                };
-
-                            let prop_type =
-                                if let Some(inner_type) = maybe_inner_type {
-                                    inner_type
-                                } else {
-                                    prop_type
-                                };
-
-                            let prop_type_ident = prop_type.ident();
-                            let good =
-                                prop_type.has_impl(TypeSpaceImpl::FromStr);
-                            let prop_name = prop_name.to_kebab_case();
-
-                            // println!(
-                            //     "{}::{}: {}; good: {}; required: {}",
-                            //     body_args.name(),
-                            //     prop_name,
-                            //     prop_type.name(),
-                            //     good,
-                            //     required,
-                            // );
-
-                            good.then(|| {
-                                let help =
-                                    description.as_ref().map(|description| {
-                                        quote! {
-                                            .help(#description)
-                                        }
-                                    });
-                                quote! {
-                                    clap::Arg::new(#prop_name)
-                                        .long(#prop_name)
-                                        .required(#required)
-                                        .value_parser(clap::value_parser!(
-                                            #prop_type_ident
-                                        ))
-                                        #help
-                                }
-                            })
-                        })
-                        .collect::<Vec<_>>()
+        let body_args = body_params.iter().map(
+            |(prop_name, required, description, prop_type_ident)| {
+                let help = description.as_ref().map(|description| {
+                    quote! {
+                        .help(#description)
+                    }
+                });
+                quote! {
+                    clap::Arg::new(#prop_name)
+                        .long(#prop_name)
+                        .required(#required)
+                        .value_parser(clap::value_parser!(
+                            #prop_type_ident
+                        ))
+                        #help
                 }
-                _ => Vec::new(),
-            };
-
-            quote! {
-                #(
-                    .arg(#body_arg)
-                )*
-            }
-        });
+            },
+        );
 
         // TODO parameter for body as input json (--body-input?)
         // TODO parameter to output a body template (--body-template?)
@@ -373,15 +387,17 @@ impl Generator {
                 #(
                     .arg(#args)
                 )*
-                #body_arg
+                #(
+                    .arg(#body_args)
+                )*
                 #about
             }
         };
 
         let op_name = format_ident!("{}", &method.operation_id);
-
         let fn_name = format_ident!("execute_{}", &method.operation_id);
 
+        // Build up the iterator processing each top-level parameter.
         let args = method
             .params
             .iter()
@@ -422,67 +438,27 @@ impl Generator {
                 }
             });
 
-        let body_arg = maybe_body_param.map(|param| {
-            let OperationParameterType::Type(type_id) = &param.typ else {
-                    unreachable!();
-                };
-
-            let body_type = self.type_space.get_type(type_id).unwrap();
-
-            let maybe_body_args = match body_type.details() {
-                typify::TypeDetails::Struct(s) => {
-                    let args = s
-                        .properties_info()
-                        .filter_map(|prop_info| {
-                            let TypeStructPropInfo {
-                                name: prop_name,
-                                description: _,
-                                required: _,
-                                type_id: body_type_id,
-                            } = prop_info;
-                            let prop_type = self
-                                .type_space
-                                .get_type(&body_type_id)
-                                .unwrap();
-                            let prop_fn = format_ident!(
-                                "{}",
-                                sanitize(prop_name, Case::Snake)
-                            );
-                            let prop_name = prop_name.to_kebab_case();
-                            let prop_type_ident = prop_type.ident();
-                            let good =
-                                prop_type.has_impl(TypeSpaceImpl::FromStr);
-                            // assert!(good || !required);
-
-                            good.then(|| {
-                                quote! {
-                                    if let Some(value) =
-                                        matches.get_one::<#prop_type_ident>(
-                                            #prop_name,
-                                        )
-                                    {
-                                        // clone here in case the arg type
-                                        // doesn't impl TryFrom<&T>
-                                        request = request.body_map(|body| {
-                                            body.#prop_fn(value.clone())
-                                        })
-                                    }
-                                }
+        // Build up the iterator processing each body property we can handle.
+        let body_args =
+            body_params
+                .iter()
+                .map(|(prop_name, _, _, prop_type_ident)| {
+                    let prop_fn =
+                        format_ident!("{}", sanitize(prop_name, Case::Snake));
+                    quote! {
+                        if let Some(value) =
+                            matches.get_one::<#prop_type_ident>(
+                                #prop_name,
+                            )
+                        {
+                            // clone here in case the arg type
+                            // doesn't impl TryFrom<&T>
+                            request = request.body_map(|body| {
+                                body.#prop_fn(value.clone())
                             })
-                        })
-                        .collect::<Vec<_>>();
-                    Some(args)
-                }
-                _ => None,
-            };
-
-            // TODO rework this.
-            maybe_body_args.map(|body_args| {
-                quote! {
-                    #( #body_args )*
-                }
-            })
-        });
+                        }
+                    }
+                });
 
         let (_, success_type) = self.extract_responses(
             method,
@@ -522,7 +498,7 @@ impl Generator {
             {
                 let mut request = self.client.#op_name();
                 #( #args )*
-                #body_arg
+                #( #body_args )*
 
                 // TODO don't want to unwrap.
                 self.over
diff --git a/progenitor-impl/tests/output/nexus-cli.out b/progenitor-impl/tests/output/nexus-cli.out
index 8e1c961..52316a2 100644
--- a/progenitor-impl/tests/output/nexus-cli.out
+++ b/progenitor-impl/tests/output/nexus-cli.out
@@ -5643,6 +5643,14 @@ impl<T: CliOverride> Cli<T> {
             request = request.organization_name(value.clone());
         }
 
+        if let Some(value) = matches.get_one::<String>("description") {
+            request = request.body_map(|body| body.description(value.clone()))
+        }
+
+        if let Some(value) = matches.get_one::<types::Name>("name") {
+            request = request.body_map(|body| body.name(value.clone()))
+        }
+
         self.over
             .execute_organization_update(matches, &mut request)
             .unwrap();
@@ -5807,6 +5815,14 @@ impl<T: CliOverride> Cli<T> {
             request = request.project_name(value.clone());
         }
 
+        if let Some(value) = matches.get_one::<String>("description") {
+            request = request.body_map(|body| body.description(value.clone()))
+        }
+
+        if let Some(value) = matches.get_one::<types::Name>("name") {
+            request = request.body_map(|body| body.name(value.clone()))
+        }
+
         self.over
             .execute_project_update(matches, &mut request)
             .unwrap();
@@ -6480,6 +6496,10 @@ impl<T: CliOverride> Cli<T> {
             request = request.body_map(|body| body.description(value.clone()))
         }
 
+        if let Some(value) = matches.get_one::<std::net::IpAddr>("ip") {
+            request = request.body_map(|body| body.ip(value.clone()))
+        }
+
         if let Some(value) = matches.get_one::<types::Name>("name") {
             request = request.body_map(|body| body.name(value.clone()))
         }
@@ -6556,6 +6576,14 @@ impl<T: CliOverride> Cli<T> {
             request = request.interface_name(value.clone());
         }
 
+        if let Some(value) = matches.get_one::<String>("description") {
+            request = request.body_map(|body| body.description(value.clone()))
+        }
+
+        if let Some(value) = matches.get_one::<types::Name>("name") {
+            request = request.body_map(|body| body.name(value.clone()))
+        }
+
         if let Some(value) = matches.get_one::<bool>("primary") {
             request = request.body_map(|body| body.primary(value.clone()))
         }
@@ -6978,6 +7006,10 @@ impl<T: CliOverride> Cli<T> {
             request = request.body_map(|body| body.dns_name(value.clone()))
         }
 
+        if let Some(value) = matches.get_one::<types::Ipv6Net>("ipv6-prefix") {
+            request = request.body_map(|body| body.ipv6_prefix(value.clone()))
+        }
+
         if let Some(value) = matches.get_one::<types::Name>("name") {
             request = request.body_map(|body| body.name(value.clone()))
         }
@@ -7034,6 +7066,18 @@ impl<T: CliOverride> Cli<T> {
             request = request.vpc_name(value.clone());
         }
 
+        if let Some(value) = matches.get_one::<String>("description") {
+            request = request.body_map(|body| body.description(value.clone()))
+        }
+
+        if let Some(value) = matches.get_one::<types::Name>("dns-name") {
+            request = request.body_map(|body| body.dns_name(value.clone()))
+        }
+
+        if let Some(value) = matches.get_one::<types::Name>("name") {
+            request = request.body_map(|body| body.name(value.clone()))
+        }
+
         self.over.execute_vpc_update(matches, &mut request).unwrap();
         let result = request.send().await;
         match result {
@@ -7250,6 +7294,14 @@ impl<T: CliOverride> Cli<T> {
             request = request.router_name(value.clone());
         }
 
+        if let Some(value) = matches.get_one::<String>("description") {
+            request = request.body_map(|body| body.description(value.clone()))
+        }
+
+        if let Some(value) = matches.get_one::<types::Name>("name") {
+            request = request.body_map(|body| body.name(value.clone()))
+        }
+
         self.over
             .execute_vpc_router_update(matches, &mut request)
             .unwrap();
@@ -7434,6 +7486,14 @@ impl<T: CliOverride> Cli<T> {
             request = request.route_name(value.clone());
         }
 
+        if let Some(value) = matches.get_one::<String>("description") {
+            request = request.body_map(|body| body.description(value.clone()))
+        }
+
+        if let Some(value) = matches.get_one::<types::Name>("name") {
+            request = request.body_map(|body| body.name(value.clone()))
+        }
+
         self.over
             .execute_vpc_router_route_update(matches, &mut request)
             .unwrap();
@@ -7542,6 +7602,10 @@ impl<T: CliOverride> Cli<T> {
             request = request.body_map(|body| body.ipv4_block(value.clone()))
         }
 
+        if let Some(value) = matches.get_one::<types::Ipv6Net>("ipv6-block") {
+            request = request.body_map(|body| body.ipv6_block(value.clone()))
+        }
+
         if let Some(value) = matches.get_one::<types::Name>("name") {
             request = request.body_map(|body| body.name(value.clone()))
         }
@@ -7610,6 +7674,14 @@ impl<T: CliOverride> Cli<T> {
             request = request.subnet_name(value.clone());
         }
 
+        if let Some(value) = matches.get_one::<String>("description") {
+            request = request.body_map(|body| body.description(value.clone()))
+        }
+
+        if let Some(value) = matches.get_one::<types::Name>("name") {
+            request = request.body_map(|body| body.name(value.clone()))
+        }
+
         self.over
             .execute_vpc_subnet_update(matches, &mut request)
             .unwrap();
@@ -8340,6 +8412,14 @@ impl<T: CliOverride> Cli<T> {
             request = request.pool_name(value.clone());
         }
 
+        if let Some(value) = matches.get_one::<String>("description") {
+            request = request.body_map(|body| body.description(value.clone()))
+        }
+
+        if let Some(value) = matches.get_one::<types::Name>("name") {
+            request = request.body_map(|body| body.name(value.clone()))
+        }
+
         self.over
             .execute_ip_pool_update(matches, &mut request)
             .unwrap();
@@ -8643,6 +8723,10 @@ impl<T: CliOverride> Cli<T> {
 
     pub async fn execute_silo_create(&self, matches: &clap::ArgMatches) {
         let mut request = self.client.silo_create();
+        if let Some(value) = matches.get_one::<String>("admin-group-name") {
+            request = request.body_map(|body| body.admin_group_name(value.clone()))
+        }
+
         if let Some(value) = matches.get_one::<String>("description") {
             request = request.body_map(|body| body.description(value.clone()))
         }
@@ -8825,6 +8909,10 @@ impl<T: CliOverride> Cli<T> {
             request = request.body_map(|body| body.description(value.clone()))
         }
 
+        if let Some(value) = matches.get_one::<String>("group-attribute-name") {
+            request = request.body_map(|body| body.group_attribute_name(value.clone()))
+        }
+
         if let Some(value) = matches.get_one::<String>("idp-entity-id") {
             request = request.body_map(|body| body.idp_entity_id(value.clone()))
         }
@@ -9683,6 +9771,14 @@ impl<T: CliOverride> Cli<T> {
             request = request.organization(value.clone());
         }
 
+        if let Some(value) = matches.get_one::<String>("description") {
+            request = request.body_map(|body| body.description(value.clone()))
+        }
+
+        if let Some(value) = matches.get_one::<types::Name>("name") {
+            request = request.body_map(|body| body.name(value.clone()))
+        }
+
         self.over
             .execute_organization_update_v1(matches, &mut request)
             .unwrap();
@@ -9847,6 +9943,14 @@ impl<T: CliOverride> Cli<T> {
             request = request.organization(value.clone());
         }
 
+        if let Some(value) = matches.get_one::<String>("description") {
+            request = request.body_map(|body| body.description(value.clone()))
+        }
+
+        if let Some(value) = matches.get_one::<types::Name>("name") {
+            request = request.body_map(|body| body.name(value.clone()))
+        }
+
         self.over
             .execute_project_update_v1(matches, &mut request)
             .unwrap();
diff --git a/progenitor-impl/tests/output/propolis-server-cli.out b/progenitor-impl/tests/output/propolis-server-cli.out
index 9709cb4..1fa6022 100644
--- a/progenitor-impl/tests/output/propolis-server-cli.out
+++ b/progenitor-impl/tests/output/propolis-server-cli.out
@@ -129,6 +129,10 @@ impl<T: CliOverride> Cli<T> {
 
     pub async fn execute_instance_ensure(&self, matches: &clap::ArgMatches) {
         let mut request = self.client.instance_ensure();
+        if let Some(value) = matches.get_one::<String>("cloud-init-bytes") {
+            request = request.body_map(|body| body.cloud_init_bytes(value.clone()))
+        }
+
         self.over
             .execute_instance_ensure(matches, &mut request)
             .unwrap();