diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 2aef71158..b9b7247dc 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -26,14 +26,6 @@ jobs:
     strategy:
       matrix:
         entry:
-          - { ruby: '3.1', grape: '1.8.0' }
-          - { ruby: '3.2', grape: '1.8.0' }
-          - { ruby: '3.3', grape: '1.8.0' }
-          - { ruby: '3.4', grape: '1.8.0' }
-          - { ruby: '3.1', grape: '2.0.0' }
-          - { ruby: '3.2', grape: '2.0.0' }
-          - { ruby: '3.3', grape: '2.0.0' }
-          - { ruby: '3.4', grape: '2.0.0' }
           - { ruby: '3.1', grape: '2.1.3' }
           - { ruby: '3.2', grape: '2.1.3' }
           - { ruby: '3.3', grape: '2.1.3' }
@@ -43,7 +35,6 @@ jobs:
           - { ruby: '3.3', grape: '2.2.0' }
           - { ruby: '3.4', grape: '2.2.0' }
           - { ruby: 'head', grape: '2.2.0' }
-          - { ruby: '3.2', grape: 'HEAD' }
           - { ruby: '3.3', grape: 'HEAD' }
           - { ruby: '3.4', grape: 'HEAD' }
     name: test (ruby=${{ matrix.entry.ruby }}, grape=${{ matrix.entry.grape }})
diff --git a/.rubocop_todo.yml b/.rubocop_todo.yml
index 811dd12a2..2caee130d 100644
--- a/.rubocop_todo.yml
+++ b/.rubocop_todo.yml
@@ -6,6 +6,14 @@
 # Note that changes in the inspected code, or installation of new
 # versions of RuboCop, may require this file to be generated again.
 
+# Offense count: 4
+# Configuration parameters: Severity.
+Style/OneClassPerFile:
+  Exclude:
+    - 'lib/grape-swagger.rb'
+    - 'spec/support/empty_model_parser.rb'
+    - 'spec/swagger_v2/guarded_endpoint_spec.rb'
+
 # Offense count: 1
 # Configuration parameters: Severity, Include.
 # Include: **/*.gemspec
@@ -21,7 +29,7 @@ Metrics/AbcSize:
 # Offense count: 32
 # Configuration parameters: CountComments, CountAsOne, AllowedMethods, AllowedPatterns.
 Metrics/MethodLength:
-  Max: 28
+  Max: 30
 
 # Offense count: 9
 # Configuration parameters: AllowedMethods, AllowedPatterns.
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 428ddb86e..d74215d6b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,11 +1,21 @@
-### 2.1.5 (Next)
+### 2.2.0 (Next)
+
+#### Breaking changes
+
+* [#978](https://github.com/ruby-grape/grape-swagger/pull/978): Bump minimum Grape to `>= 2.1` (was `>= 1.7`); drop Grape 1.8/2.0 CI rows. See [UPGRADING](UPGRADING.md) - [@numbata](https://github.com/numbata).
+* [#978](https://github.com/ruby-grape/grape-swagger/pull/978): On Grape 3.2+, declare swagger-only types under `documentation: { type: 'Object' }` instead of `params { type: 'Object' }` - [@numbata](https://github.com/numbata).
+* [#978](https://github.com/ruby-grape/grape-swagger/pull/978): On Grape 3.2+, custom type classes used via `type: MyClass` must implement `MyClass.parse(value)` - [@numbata](https://github.com/numbata).
+* Your contribution here.
 
 #### Features
 
+* [#978](https://github.com/ruby-grape/grape-swagger/pull/978): Accept string-keyed `api_documentation` / `specific_api_documentation` and a `:description` alias for `:desc` - [@numbata](https://github.com/numbata).
 * Your contribution here.
 
 #### Fixes
 
+* [#978](https://github.com/ruby-grape/grape-swagger/pull/978): Pass keyword arguments to `desc` to fix Grape 3.2 deprecation - [@numbata](https://github.com/numbata).
+* [#978](https://github.com/ruby-grape/grape-swagger/pull/978): On Grape 3.3+, recover multi-type params (`type: [A, B]`) from `VariantCollectionCoercer` so swagger reflects the first declared type instead of the coercer's `#inspect` string - [@numbata](https://github.com/numbata).
 * Your contribution here.
 
 ### 2.1.4 (2026-02-02)
diff --git a/README.md b/README.md
index e83fd48af..466c09c12 100644
--- a/README.md
+++ b/README.md
@@ -125,7 +125,8 @@ The following versions of grape, grape-entity and grape-swagger can currently be
 | >= 1.0.0              | 2.0          | >= 1.3.0                | >= 0.5.0     | >= 2.4.1      |
 | >= 2.0.0              | 2.0          | >= 1.7.0                | >= 0.5.0     | >= 2.4.1      |
 | >= 2.0.0 ... <= 2.1.2 | 2.0          | >= 1.8.0 ... < 2.3.0    | >= 0.5.0     | >= 2.4.1      |
-| > 2.1.2               | 2.0          | >= 1.8.0 ... < 4.0      | >= 0.5.0     | >= 2.4.1      |
+| >= 2.1.3 ... < 2.2.0  | 2.0          | >= 1.8.0 ... < 4.0      | >= 0.5.0     | >= 2.4.1      |
+| >= 2.2.0              | 2.0          | >= 2.1 ... < 4.0        | >= 0.5.0     | >= 2.4.1      |
 
 
 ## Swagger-Spec <a name="swagger-spec"></a>
@@ -498,6 +499,8 @@ add_swagger_documentation \
    api_documentation: { desc: 'Reticulated splines API swagger-compatible documentation.' }
 ```
 
+`:description` is accepted as an alias for `:desc` (when both are supplied, `:desc` wins; an explicit `desc: nil` is respected and does not fall through). String keys (e.g. when loading from YAML/JSON) are accepted too.
+
 #### specific_api_documentation
 
 Customize the Swagger API specific documentation route, typically contains a `desc` field. The default description is "Swagger compatible API description for specific API".
diff --git a/UPGRADING.md b/UPGRADING.md
index 1df6264cd..9b620f0e8 100644
--- a/UPGRADING.md
+++ b/UPGRADING.md
@@ -1,5 +1,26 @@
 ## Upgrading Grape-swagger
 
+### Upgrading to >= 2.2.0
+
+- **Minimum Grape version is now `>= 2.1`** (was `>= 1.7`). Grape 1.8.0 and 2.0.0 cannot be used on Ruby 3.3+ because of an upstream Mustermann/forwardable incompatibility; the CI rows for those combinations were already failing on `master` and have been removed.
+- **`type: 'Object'` (and other string type names) in `params` blocks**: Grape 3.2+ rejects string type names. If you previously declared a swagger-only documentation hint via `params { optional :foo, type: 'Object' }`, move the type under `documentation:`:
+
+  ```ruby
+  optional :foo, documentation: { type: 'Object' }
+  ```
+
+  grape-swagger picks the type up from the merged settings unchanged, so the swagger output is identical.
+- **Custom type classes** used via `type: MyClass` must implement `MyClass.parse(value)` (arity 1) on Grape 3.2+; otherwise Grape's dry-types lookup raises `ArgumentError`. `Grape::Entity` already provides `parse`; `Representable::Decorator` and plain Ruby classes need to define it explicitly:
+
+  ```ruby
+  class MyType
+    def self.parse(value) = new(value)
+    # ...
+  end
+  ```
+
+- **Multi-type params (`type: [A, B]`) on Grape 3.3+**: swagger output now reflects the first declared type (e.g. `type: [Integer, Float]` produces `"integer"`). Previously, Grape 3.3 serialized the `VariantCollectionCoercer` wrapper via `#to_s`, leaking `"#<Grape::Validations::Types::VariantCollectionCoercer:0x...>"` into the documentation. No action required, but if you were programmatically post-processing that string, the fix will change the output.
+
 ### Upgrading to >= x.y.z
 
 - Grape-swagger now documents array parameters within an object schema in Swagger. This aligns with grape's JSON structure requirements and ensures the documentation is correct.
diff --git a/grape-swagger.gemspec b/grape-swagger.gemspec
index d88943efa..ce9d6b7fe 100644
--- a/grape-swagger.gemspec
+++ b/grape-swagger.gemspec
@@ -15,7 +15,7 @@ Gem::Specification.new do |s|
   s.metadata['rubygems_mfa_required'] = 'true'
 
   s.required_ruby_version = '>= 3.1'
-  s.add_dependency 'grape', '>= 1.7', '< 4.0'
+  s.add_dependency 'grape', '>= 2.1', '< 4.0'
 
   s.files = Dir['lib/**/*', '*.md', 'LICENSE.txt', 'grape-swagger.gemspec']
   s.require_paths = ['lib']
diff --git a/lib/grape-swagger/doc_methods.rb b/lib/grape-swagger/doc_methods.rb
index 9e22499d7..8cbc74286 100644
--- a/lib/grape-swagger/doc_methods.rb
+++ b/lib/grape-swagger/doc_methods.rb
@@ -86,14 +86,14 @@ def setup(options)
       # for available options see #defaults
       target_class     = options[:target_class]
       guard            = options[:swagger_endpoint_guard]
-      api_doc          = options[:api_documentation].dup
-      specific_api_doc = options[:specific_api_documentation].dup
+      api_doc          = options[:api_documentation].transform_keys(&:to_sym)
+      specific_api_doc = options[:specific_api_documentation].transform_keys(&:to_sym)
 
       class_variables_from(options)
 
       setup_formatter(options[:format])
 
-      desc api_doc.delete(:desc), api_doc
+      desc(pop_desc(api_doc), **api_doc)
 
       instance_eval(guard) unless guard.nil?
 
@@ -105,7 +105,9 @@ def setup(options)
           .output_path_definitions(target_class.combined_namespace_routes, self, target_class, options)
       end
 
-      desc specific_api_doc.delete(:desc), { params: specific_api_doc.delete(:params) || {}, **specific_api_doc }
+      specific_desc   = pop_desc(specific_api_doc)
+      specific_params = specific_api_doc.delete(:params) || {}
+      desc(specific_desc, params: specific_params, **specific_api_doc)
 
       params do
         requires :name, type: String, desc: 'Resource name of mounted API'
@@ -136,5 +138,13 @@ def setup_formatter(formatter)
 
       FORMATTER_METHOD.each { |method| send(method, formatter) }
     end
+
+    private
+
+    # :desc takes precedence over :description; explicit nil under :desc wins
+    # (don't fall through on nil — that would silently substitute :description).
+    def pop_desc(doc)
+      doc.key?(:desc) ? doc.delete(:desc) : doc.delete(:description)
+    end
   end
 end
diff --git a/lib/grape-swagger/request_param_parsers/route.rb b/lib/grape-swagger/request_param_parsers/route.rb
index d3d27d20c..2ffa9ee92 100644
--- a/lib/grape-swagger/request_param_parsers/route.rb
+++ b/lib/grape-swagger/request_param_parsers/route.rb
@@ -19,8 +19,9 @@ def parse
         stackable_values = route.app&.inheritable_setting&.namespace_stackable
 
         path_params = build_path_params(stackable_values)
+        variant_types = collect_variant_types(stackable_values)
 
-        fulfill_params(path_params)
+        fulfill_params(path_params, variant_types)
       end
 
       private
@@ -47,7 +48,51 @@ def fetch_inherited_params(stackable_values)
         end
       end
 
-      def fulfill_params(path_params)
+      # On Grape >= 3.3 `type: [A, B]` is documented in route.params via the
+      # VariantCollectionCoercer's `#to_s`, which loses the original type list.
+      # On earlier versions the same param appears as the stringified Array
+      # `"[A, B]"` and the existing regex in DataType.parse_multi_type already
+      # handles it; the recovery here is a no-op for those versions.
+      #
+      # The live coercer is still reachable through the CoerceValidator's
+      # @converter, so we rebuild a name => types map keyed by the fully-qualified
+      # param name (e.g. "group[inner]") to match route.params keys and avoid
+      # clobbering same-named params at outer scopes.
+      #
+      # NOTE: @converter, @types, and @scope are private Grape ivars. If Grape
+      # renames them, this method silently returns {} and swagger falls back to
+      # the pre-fix broken output (coercer inspect string) — not a crash.
+      def collect_variant_types(stackable_values)
+        variant_types = {}
+        return variant_types unless defined?(Grape::Validations::Types::VariantCollectionCoercer) &&
+                                    defined?(Grape::Validations::Validators::CoerceValidator) &&
+                                    stackable_values.respond_to?(:[])
+
+        # StackableValues#[] concatenates inheritance levels and always returns
+        # a flat Array of validator instances — no wrapping or flattening needed.
+        stackable_values[:validations].each do |validator|
+          next unless validator.is_a?(Grape::Validations::Validators::CoerceValidator)
+
+          converter = validator.instance_variable_get(:@converter)
+          next unless converter.is_a?(Grape::Validations::Types::VariantCollectionCoercer)
+
+          # `.to_a` preserves the user-declared order for both Array and Set
+          # storage shapes; `DataType.parse_multi_type` uses `.first` downstream.
+          types = converter.instance_variable_get(:@types).to_a
+          next if types.empty?
+
+          scope = validator.instance_variable_get(:@scope)
+          next unless scope.respond_to?(:full_name)
+
+          validator.attrs.each do |attr|
+            variant_types[scope.full_name(attr)] = types
+          end
+        end
+
+        variant_types
+      end
+
+      def fulfill_params(path_params, variant_types)
         # Merge path params options into route params
         route.params.each_with_object({}) do |(param, definition), accum|
           # The route.params hash includes both parametrized params (with a string as a key)
@@ -57,10 +102,18 @@ def fulfill_params(path_params)
           next if param.is_a?(String) && accum.key?(key)
 
           defined_options = definition.is_a?(Hash) ? definition : {}
+          defined_options = restore_variant_type(defined_options, param, variant_types)
           value = (path_params[param] || {}).merge(defined_options)
           accum[key] = value.empty? ? DEFAULT_PARAM_TYPE : value
         end
       end
+
+      def restore_variant_type(defined_options, param, variant_types)
+        types = variant_types[param.to_s]
+        return defined_options unless types
+
+        defined_options.merge(type: types)
+      end
     end
   end
 end
diff --git a/lib/grape-swagger/version.rb b/lib/grape-swagger/version.rb
index 24e1e6d97..cb9a6be28 100644
--- a/lib/grape-swagger/version.rb
+++ b/lib/grape-swagger/version.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module GrapeSwagger
-  VERSION = '2.1.5'
+  VERSION = '2.2.0'
 end
diff --git a/spec/lib/endpoint_spec.rb b/spec/lib/endpoint_spec.rb
index ba6724488..6e3884941 100644
--- a/spec/lib/endpoint_spec.rb
+++ b/spec/lib/endpoint_spec.rb
@@ -4,7 +4,8 @@
 
 describe Grape::Endpoint do
   subject do
-    described_class.new(Grape::Util::InheritableSetting.new, path: '/', method: :get)
+    # Grape >= HEAD requires :for (the owner API class) when constructing an Endpoint.
+    described_class.new(Grape::Util::InheritableSetting.new, path: '/', method: :get, for: Class.new(Grape::API))
   end
 
   describe '.content_types_for' do
diff --git a/spec/support/model_parsers/mock_parser.rb b/spec/support/model_parsers/mock_parser.rb
index 13bdcc04c..de6d24c00 100644
--- a/spec/support/model_parsers/mock_parser.rb
+++ b/spec/support/model_parsers/mock_parser.rb
@@ -72,7 +72,13 @@ class RecursiveModel < OpenStruct; end
       class DocumentedHashAndArrayModel < OpenStruct; end
 
       module NestedModule
-        class ApiResponse < OpenStruct; end
+        class ApiResponse < OpenStruct
+          # Grape 3.2+ requires unknown types to implement .parse (arity 1) to pass the
+          # Types.custom? check and avoid a dry-types lookup that would raise ArgumentError.
+          # The implementation is minimal because these tests exercise swagger doc generation
+          # only, not actual request coercion.
+          def self.parse(val) = val
+        end
       end
     end
   end
diff --git a/spec/support/model_parsers/representable_parser.rb b/spec/support/model_parsers/representable_parser.rb
index 2102ce8aa..d56fbd4de 100644
--- a/spec/support/model_parsers/representable_parser.rb
+++ b/spec/support/model_parsers/representable_parser.rb
@@ -99,6 +99,11 @@ class ApiResponse < Representable::Decorator
 
           property :status, documentation: { type: String }
           property :error, documentation: { type: ::Entities::ApiError }
+
+          # Grape 3.2+ requires unknown types to implement .parse (arity 1) to pass the
+          # Types.custom? check. Representable::Decorator does not define parse, so we add
+          # a minimal pass-through sufficient for documentation-generation tests.
+          def self.parse(val) = val
         end
       end
 
diff --git a/spec/swagger_v2/api_documentation_spec.rb b/spec/swagger_v2/api_documentation_spec.rb
index cd0062a96..34f3fc01f 100644
--- a/spec/swagger_v2/api_documentation_spec.rb
+++ b/spec/swagger_v2/api_documentation_spec.rb
@@ -23,4 +23,64 @@
       'Swagger compatible API description for specific API'
     ]
   end
+
+  context 'when api_documentation is string-keyed' do
+    let(:api) do
+      Class.new(Grape::API) do
+        add_swagger_documentation api_documentation: { 'desc' => 'String-keyed description' }
+      end
+    end
+
+    it 'accepts string keys' do
+      expect(subject.first[:description]).to eq('String-keyed description')
+    end
+  end
+
+  context 'when api_documentation uses :description instead of :desc' do
+    let(:api) do
+      Class.new(Grape::API) do
+        add_swagger_documentation api_documentation: { description: 'Via description key' }
+      end
+    end
+
+    it 'falls back to :description' do
+      expect(subject.first[:description]).to eq('Via description key')
+    end
+  end
+
+  context 'when both :desc and :description are supplied' do
+    let(:api) do
+      Class.new(Grape::API) do
+        add_swagger_documentation api_documentation: { desc: 'Desc wins', description: 'Description loses' }
+      end
+    end
+
+    it ':desc takes precedence' do
+      expect(subject.pluck(:description)).to include('Desc wins')
+    end
+  end
+
+  context 'when :desc is explicitly nil' do
+    let(:api) do
+      Class.new(Grape::API) do
+        add_swagger_documentation api_documentation: { desc: nil, description: 'fallback' }
+      end
+    end
+
+    it 'respects the explicit nil and does not fall through to :description' do
+      expect(subject.pluck(:description)).not_to include('fallback')
+    end
+  end
+
+  context 'when specific_api_documentation uses :description' do
+    let(:api) do
+      Class.new(Grape::API) do
+        add_swagger_documentation specific_api_documentation: { description: 'Specific via description' }
+      end
+    end
+
+    it 'accepts :description on the specific endpoint too' do
+      expect(subject.pluck(:description)).to include('Specific via description')
+    end
+  end
 end
diff --git a/spec/swagger_v2/param_multi_type_spec.rb b/spec/swagger_v2/param_multi_type_spec.rb
index afcc10b0a..89d9486c1 100644
--- a/spec/swagger_v2/param_multi_type_spec.rb
+++ b/spec/swagger_v2/param_multi_type_spec.rb
@@ -50,6 +50,35 @@ def app
     ]
   end
 
+  describe 'with non-string primary type' do
+    def app
+      Class.new(Grape::API) do
+        format :json
+
+        desc 'action' do
+          consumes ['application/x-www-form-urlencoded']
+        end
+        params do
+          requires :int_first, type: [Integer, Float]
+          requires :nested_group, type: Hash do
+            requires :nested_int, type: [Integer, Float]
+          end
+        end
+        post :action do
+          { message: 'hi' }
+        end
+
+        add_swagger_documentation
+      end
+    end
+
+    it 'recovers the first variant type, not a hardcoded fallback' do
+      types = subject.to_h { |p| [p['name'], p['type']] }
+      expect(types['int_first']).to eq('integer')
+      expect(types['nested_group[nested_int]']).to eq('integer')
+    end
+  end
+
   describe 'header params' do
     def app
       Class.new(Grape::API) do
diff --git a/spec/swagger_v2/params_example_spec.rb b/spec/swagger_v2/params_example_spec.rb
index fbddf7cca..f3504e03d 100644
--- a/spec/swagger_v2/params_example_spec.rb
+++ b/spec/swagger_v2/params_example_spec.rb
@@ -11,7 +11,10 @@ def app
         params :common_params do
           requires :id, type: Integer, documentation: { example: 123 }
           optional :name, type: String, documentation: { example: 'Person' }
-          optional :obj, type: 'Object', documentation: { example: { 'foo' => 'bar' } }
+          # 'Object' is not a valid Grape coercion type; it is a swagger documentation-only hint.
+          # Grape 3.2+ rejects string type names in params blocks, so the type lives in
+          # documentation: where grape-swagger picks it up via ParseParams#call settings merge.
+          optional :obj, documentation: { type: 'Object', example: { 'foo' => 'bar' } }
         end
       end