diff --git a/packages/catalog-realm/AiAppGenerator/create-product-requirements-command.ts b/packages/catalog-realm/AiAppGenerator/create-product-requirements-command.ts
index d87ce8340b..5c244dc9b5 100644
--- a/packages/catalog-realm/AiAppGenerator/create-product-requirements-command.ts
+++ b/packages/catalog-realm/AiAppGenerator/create-product-requirements-command.ts
@@ -59,13 +59,10 @@ export default class CreateProductRequirementsInstance extends Command<
     let prdCard = new ProductRequirementDocument();
 
     let saveCardCommand = new SaveCardCommand(this.commandContext);
-    let SaveCardInputType = await saveCardCommand.getInputType();
-    await saveCardCommand.execute(
-      new SaveCardInputType({
-        realm: input.realm,
-        card: prdCard,
-      }),
-    );
+    await saveCardCommand.execute({
+      realm: input.realm,
+      card: prdCard,
+    });
     // Get patch command, this takes the card and returns a command that can be used to patch the card
     let patchPRDCommand = new PatchCardCommand(this.commandContext, {
       cardType: ProductRequirementDocument,
diff --git a/packages/host/app/services/command-service.ts b/packages/host/app/services/command-service.ts
index 29963760da..1d1c6faab1 100644
--- a/packages/host/app/services/command-service.ts
+++ b/packages/host/app/services/command-service.ts
@@ -82,11 +82,17 @@ export default class CommandService extends Service {
       // Get the input type and validate/construct the payload
       let InputType = await command.getInputType();
 
-      // Construct a new instance of the input type with the payload
-      let typedInput = new InputType({
-        ...toolCall.arguments.attributes,
-        ...toolCall.arguments.relationships,
-      });
+      // Construct a new instance of the input type with the
+      // The input is undefined if the command has no input type
+      let typedInput;
+      if (InputType) {
+        typedInput = new InputType({
+          ...toolCall.arguments.attributes,
+          ...toolCall.arguments.relationships,
+        });
+      } else {
+        typedInput = undefined;
+      }
       let res = await command.execute(typedInput);
       await this.matrixService.sendReactionEvent(
         event.room_id!,
@@ -131,10 +137,16 @@ export default class CommandService extends Service {
         // Get the input type and validate/construct the payload
         let InputType = await commandToRun.getInputType();
         // Construct a new instance of the input type with the payload
-        let typedInput = new InputType({
-          ...payload.attributes,
-          ...payload.relationships,
-        });
+        // The input is undefined if the command has no input type
+        let typedInput;
+        if (InputType) {
+          typedInput = new InputType({
+            ...payload.attributes,
+            ...payload.relationships,
+          });
+        } else {
+          typedInput = undefined;
+        }
         [res] = await all([
           await commandToRun.execute(typedInput),
           await timeout(DELAY_FOR_APPLYING_UI), // leave a beat for the "applying" state of the UI to be shown
diff --git a/packages/host/tests/integration/commands/commands-calling-test.gts b/packages/host/tests/integration/commands/commands-calling-test.gts
new file mode 100644
index 0000000000..066b13486e
--- /dev/null
+++ b/packages/host/tests/integration/commands/commands-calling-test.gts
@@ -0,0 +1,191 @@
+import { getOwner } from '@ember/owner';
+import { RenderingTestContext } from '@ember/test-helpers';
+
+import { module, test } from 'qunit';
+
+import { Command, CommandContext } from '@cardstack/runtime-common';
+
+import type CommandService from '@cardstack/host/services/command-service';
+
+import RealmService from '@cardstack/host/services/realm';
+
+import { lookupService, testRealmURL, testRealmInfo } from '../../helpers';
+import {
+  CardDef,
+  StringField,
+  contains,
+  field,
+  setupBaseRealm,
+} from '../../helpers/base-realm';
+import { setupRenderingTest } from '../../helpers/setup';
+
+class StubRealmService extends RealmService {
+  get defaultReadableRealm() {
+    return {
+      path: testRealmURL,
+      info: testRealmInfo,
+    };
+  }
+}
+
+module('Integration | commands | commands-calling', function (hooks) {
+  setupRenderingTest(hooks);
+  setupBaseRealm(hooks);
+  let commandContext: CommandContext;
+
+  hooks.beforeEach(function (this: RenderingTestContext) {
+    getOwner(this)!.register('service:realm', StubRealmService);
+
+    let commandService = lookupService<CommandService>('command-service');
+    commandContext = commandService.commandContext;
+  });
+
+  test('can be called with a card as input', async function (assert) {
+    class CommandInput extends CardDef {
+      @field inputField1 = contains(StringField);
+      @field inputField2 = contains(StringField);
+    }
+    class CommandOutput extends CardDef {
+      @field outputField = contains(StringField);
+    }
+
+    class ExampleCommand extends Command<CommandInput, CommandOutput> {
+      inputType = CommandInput;
+
+      async getInputType() {
+        return CommandInput;
+      }
+
+      async run(input: CommandInput) {
+        return new CommandOutput({
+          outputField: `Hello ${input.inputField1}${input.inputField2}`,
+        });
+      }
+    }
+    let exampleCommand = new ExampleCommand(commandContext);
+
+    const InputType = await exampleCommand.getInputType();
+    let input = new InputType({
+      inputField1: 'World',
+      inputField2: '!',
+    });
+    let output = await exampleCommand.execute(input);
+    assert.strictEqual(output.outputField, 'Hello World!');
+  });
+
+  test('can be called with plain object as input', async function (assert) {
+    class CommandInput extends CardDef {
+      @field inputField1 = contains(StringField);
+      @field inputField2 = contains(StringField);
+    }
+    class CommandOutput extends CardDef {
+      @field outputField = contains(StringField);
+    }
+
+    class ExampleCommand extends Command<CommandInput, CommandOutput> {
+      inputType = CommandInput;
+
+      async getInputType() {
+        return CommandInput;
+      }
+
+      async run(input: CommandInput) {
+        return new CommandOutput({
+          outputField: `Hello ${input.inputField1}${input.inputField2}`,
+        });
+      }
+    }
+    let exampleCommand = new ExampleCommand(commandContext);
+    let output = await exampleCommand.execute({
+      inputField1: 'World',
+      inputField2: '!',
+    });
+    assert.strictEqual(output.outputField, 'Hello World!');
+  });
+
+  test('can call a command with just some of the fields', async function (assert) {
+    class CommandInput extends CardDef {
+      @field inputField1 = contains(StringField);
+      @field inputField2 = contains(StringField);
+    }
+    class CommandOutput extends CardDef {
+      @field outputField = contains(StringField);
+    }
+
+    class ExampleCommand extends Command<CommandInput, CommandOutput> {
+      inputType = CommandInput;
+
+      async getInputType() {
+        return CommandInput;
+      }
+
+      async run(input: CommandInput) {
+        return new CommandOutput({
+          outputField: `Hello ${input.inputField1}${input.inputField2}`,
+        });
+      }
+    }
+    let exampleCommand = new ExampleCommand(commandContext);
+
+    let output = await exampleCommand.execute({
+      inputField1: 'World',
+    });
+    assert.strictEqual(output.outputField, 'Hello Worldundefined');
+  });
+
+  test('CardDef fields are optional', async function (assert) {
+    class CommandInput extends CardDef {
+      @field inputField1 = contains(StringField);
+      @field inputField2 = contains(StringField);
+    }
+    class CommandOutput extends CardDef {
+      @field outputField = contains(StringField);
+    }
+
+    class ExampleCommand extends Command<CommandInput, CommandOutput> {
+      inputType = CommandInput;
+
+      async getInputType() {
+        return CommandInput;
+      }
+
+      async run(input: CommandInput) {
+        return new CommandOutput({
+          outputField: `Hello ${input.inputField1}${input.inputField2}`,
+        });
+      }
+    }
+    let exampleCommand = new ExampleCommand(commandContext);
+
+    let output = await exampleCommand.execute({
+      inputField1: 'World',
+      inputField2: '!',
+      title: 'test',
+    });
+    assert.strictEqual(output.outputField, 'Hello World!');
+  });
+
+  test('Commands work without taking input', async function (assert) {
+    class CommandOutput extends CardDef {
+      @field outputField = contains(StringField);
+    }
+
+    class ExampleCommand extends Command<undefined, CommandOutput> {
+      inputType = undefined;
+
+      async getInputType() {
+        return undefined;
+      }
+
+      async run() {
+        return new CommandOutput({
+          outputField: 'Hello',
+        });
+      }
+    }
+    let exampleCommand = new ExampleCommand(commandContext);
+
+    let output = await exampleCommand.execute(undefined);
+    assert.strictEqual(output.outputField, 'Hello');
+  });
+});
diff --git a/packages/runtime-common/commands.ts b/packages/runtime-common/commands.ts
index 2a8cdd3e64..7762b12965 100644
--- a/packages/runtime-common/commands.ts
+++ b/packages/runtime-common/commands.ts
@@ -1,3 +1,4 @@
+import { isCardDef } from './code-ref';
 import { Deferred } from './deferred';
 import type * as CardAPI from 'https://cardstack.com/base/card-api';
 import { CardDef } from 'https://cardstack.com/base/card-api';
@@ -51,7 +52,9 @@ export abstract class Command<
   CommandConfiguration extends any | undefined = undefined,
 > {
   // Is this actually type checking ?
-  abstract getInputType(): Promise<{ new (args: any): CardInputType }>; // TODO: can we do better than any here?
+  abstract getInputType(): Promise<
+    { new (args?: Partial<CardInputType>): CardInputType } | undefined
+  >; // TODO: can we do better than any here?
 
   invocations: CommandInvocation<CardInputType, CardResultType>[] = [];
 
@@ -66,20 +69,39 @@ export abstract class Command<
     protected readonly configuration?: CommandConfiguration | undefined, // we'd like this to be required *if* CommandConfiguration is defined, and allow the user to skip it when CommandConfiguration is undefined
   ) {}
 
-  async execute(input: CardInputType): Promise<CardResultType> {
+  async execute(
+    input: CardInputType extends CardDef | undefined
+      ? CardInputType | Partial<Omit<CardInputType, keyof CardDef>>
+      : never,
+  ): Promise<CardResultType> {
     // internal bookkeeping
     // todo: support for this.runTask being defined
     // runTask would be an ember task, run would just be a normal function
 
+    let inputCard: CardInputType;
+    if (input === undefined) {
+      inputCard = undefined as CardInputType;
+    } else if (isCardDef(input.constructor)) {
+      inputCard = input as CardInputType;
+    } else {
+      let InputType = await this.getInputType();
+      if (!InputType) {
+        throw new Error('Input provided but no input type found');
+      } else {
+        inputCard = new InputType(
+          input as Partial<CardInputType>,
+        ) as CardInputType;
+      }
+    }
     let invocation = new CommandInvocation<CardInputType, CardResultType>(
-      input,
+      inputCard,
     );
 
     this.invocations.push(invocation);
     this.nextCompletionDeferred.fulfill(invocation.promise);
 
     try {
-      let result = await this.run(input);
+      let result = await this.run(inputCard);
       invocation.fulfill(result);
       return result;
     } catch (error) {