feat(api): Add support for claude-mythos-preview

stainless-app[bot] · stainless-app[bot] · commit d4057b0a9559 · 2026-04-07T17:45:51.000Z
diff --git a/.stats.yml b/.stats.yml
@@ -1,4 +1,4 @@
 configured_endpoints: 34
-openapi_spec_url: https://storage.googleapis.com/stainless-sdk-openapi-specs/anthropic%2Fanthropic-efe26b096126c693462514b8cbd3ec3e376569232becbfb730cd26fb31c7c7e3.yml
+openapi_spec_url: https://storage.googleapis.com/stainless-sdk-openapi-specs/anthropic%2Fanthropic-04225437444990f383d0581df2f07022baab6ad510de0f3a8bd6b07c38d83cc9.yml
 openapi_spec_hash: cae9199aabfd7b87f0ff2dcc10760c92
-config_hash: e1ebf6470ea96e5b7bf02520fbeeed0a
+config_hash: fcc34074db6eaf64bc99b578c6c82c61
diff --git a/src/resources/beta/messages/batches.ts b/src/resources/beta/messages/batches.ts
@@ -634,14 +634,9 @@ export namespace BatchCreateParams {
       system?: string | Array<BetaMessagesAPI.BetaTextBlockParam>;
 
       /**
-       * Amount of randomness injected into the response.
-       *
-       * Defaults to `1.0`. Ranges from `0.0` to `1.0`. Use `temperature` closer to `0.0`
-       * for analytical / multiple choice, and closer to `1.0` for creative and
-       * generative tasks.
-       *
-       * Note that even with `temperature` of `0.0`, the results will not be fully
-       * deterministic.
+       * @deprecated Deprecated. Models released after Claude Opus 4.6 do not support
+       * setting temperature. A value of 1.0 of will be accepted for backwards
+       * compatibility, all other values will be rejected with a 400 error.
        */
       temperature?: number;
 
@@ -744,26 +739,15 @@ export namespace BatchCreateParams {
       tools?: Array<BetaMessagesAPI.BetaToolUnion>;
 
       /**
-       * Only sample from the top K options for each subsequent token.
-       *
-       * Used to remove "long tail" low probability responses.
-       * [Learn more technical details here](https://towardsdatascience.com/how-to-sample-from-language-models-682bceb97277).
-       *
-       * Recommended for advanced use cases only. You usually only need to use
-       * `temperature`.
+       * @deprecated Deprecated. Models released after Claude Opus 4.6 do not accept
+       * top_k; any value will be rejected with a 400 error.
        */
       top_k?: number;
 
       /**
-       * Use nucleus sampling.
-       *
-       * In nucleus sampling, we compute the cumulative distribution over all the options
-       * for each subsequent token in decreasing probability order and cut it off once it
-       * reaches a particular probability specified by `top_p`. You should either alter
-       * `temperature` or `top_p`, but not both.
-       *
-       * Recommended for advanced use cases only. You usually only need to use
-       * `temperature`.
+       * @deprecated Deprecated. Models released after Claude Opus 4.6 do not support
+       * setting top_p. A value >= 0.99 will be accepted for backwards compatibility, all
+       * other values will be rejected with a 400 error.
        */
       top_p?: number;
     }
diff --git a/src/resources/beta/messages/messages.ts b/src/resources/beta/messages/messages.ts
@@ -201,7 +201,7 @@ export class Messages extends APIResource {
    * const betaMessageTokensCount =
    *   await client.beta.messages.countTokens({
    *     messages: [{ content: 'string', role: 'user' }],
-   *     model: 'claude-opus-4-6',
+   *     model: 'claude-mythos-preview',
    *   });
    * ```
    */
@@ -3714,14 +3714,9 @@ export interface MessageCreateParamsBase {
   system?: string | Array<BetaTextBlockParam>;
 
   /**
-   * Body param: Amount of randomness injected into the response.
-   *
-   * Defaults to `1.0`. Ranges from `0.0` to `1.0`. Use `temperature` closer to `0.0`
-   * for analytical / multiple choice, and closer to `1.0` for creative and
-   * generative tasks.
-   *
-   * Note that even with `temperature` of `0.0`, the results will not be fully
-   * deterministic.
+   * @deprecated Deprecated. Models released after Claude Opus 4.6 do not support
+   * setting temperature. A value of 1.0 of will be accepted for backwards
+   * compatibility, all other values will be rejected with a 400 error.
    */
   temperature?: number;
 
@@ -3824,26 +3819,15 @@ export interface MessageCreateParamsBase {
   tools?: Array<BetaToolUnion>;
 
   /**
-   * Body param: Only sample from the top K options for each subsequent token.
-   *
-   * Used to remove "long tail" low probability responses.
-   * [Learn more technical details here](https://towardsdatascience.com/how-to-sample-from-language-models-682bceb97277).
-   *
-   * Recommended for advanced use cases only. You usually only need to use
-   * `temperature`.
+   * @deprecated Deprecated. Models released after Claude Opus 4.6 do not accept
+   * top_k; any value will be rejected with a 400 error.
    */
   top_k?: number;
 
   /**
-   * Body param: Use nucleus sampling.
-   *
-   * In nucleus sampling, we compute the cumulative distribution over all the options
-   * for each subsequent token in decreasing probability order and cut it off once it
-   * reaches a particular probability specified by `top_p`. You should either alter
-   * `temperature` or `top_p`, but not both.
-   *
-   * Recommended for advanced use cases only. You usually only need to use
-   * `temperature`.
+   * @deprecated Deprecated. Models released after Claude Opus 4.6 do not support
+   * setting top_p. A value >= 0.99 will be accepted for backwards compatibility, all
+   * other values will be rejected with a 400 error.
    */
   top_p?: number;
 
diff --git a/src/resources/completions.ts b/src/resources/completions.ts
@@ -24,7 +24,7 @@ export class Completions extends APIResource {
    * ```ts
    * const completion = await client.completions.create({
    *   max_tokens_to_sample: 256,
-   *   model: 'claude-opus-4-6',
+   *   model: 'claude-mythos-preview',
    *   prompt: '\n\nHuman: Hello, world!\n\nAssistant:',
    * });
    * ```
diff --git a/src/resources/messages/messages.ts b/src/resources/messages/messages.ts
@@ -177,7 +177,7 @@ export class Messages extends APIResource {
    * const messageTokensCount =
    *   await client.messages.countTokens({
    *     messages: [{ content: 'string', role: 'user' }],
-   *     model: 'claude-opus-4-6',
+   *     model: 'claude-mythos-preview',
    *   });
    * ```
    */
@@ -1075,6 +1075,7 @@ export interface Metadata {
  * details and options.
  */
 export type Model =
+  | 'claude-mythos-preview'
   | 'claude-opus-4-6'
   | 'claude-sonnet-4-6'
   | 'claude-haiku-4-5'
@@ -2814,14 +2815,9 @@ export interface MessageCreateParamsBase {
   system?: string | Array<TextBlockParam>;
 
   /**
-   * Amount of randomness injected into the response.
-   *
-   * Defaults to `1.0`. Ranges from `0.0` to `1.0`. Use `temperature` closer to `0.0`
-   * for analytical / multiple choice, and closer to `1.0` for creative and
-   * generative tasks.
-   *
-   * Note that even with `temperature` of `0.0`, the results will not be fully
-   * deterministic.
+   * @deprecated Deprecated. Models released after Claude Opus 4.6 do not support
+   * setting temperature. A value of 1.0 of will be accepted for backwards
+   * compatibility, all other values will be rejected with a 400 error.
    */
   temperature?: number;
 
@@ -2924,26 +2920,15 @@ export interface MessageCreateParamsBase {
   tools?: Array<ToolUnion>;
 
   /**
-   * Only sample from the top K options for each subsequent token.
-   *
-   * Used to remove "long tail" low probability responses.
-   * [Learn more technical details here](https://towardsdatascience.com/how-to-sample-from-language-models-682bceb97277).
-   *
-   * Recommended for advanced use cases only. You usually only need to use
-   * `temperature`.
+   * @deprecated Deprecated. Models released after Claude Opus 4.6 do not accept
+   * top_k; any value will be rejected with a 400 error.
    */
   top_k?: number;
 
   /**
-   * Use nucleus sampling.
-   *
-   * In nucleus sampling, we compute the cumulative distribution over all the options
-   * for each subsequent token in decreasing probability order and cut it off once it
-   * reaches a particular probability specified by `top_p`. You should either alter
-   * `temperature` or `top_p`, but not both.
-   *
-   * Recommended for advanced use cases only. You usually only need to use
-   * `temperature`.
+   * @deprecated Deprecated. Models released after Claude Opus 4.6 do not support
+   * setting top_p. A value >= 0.99 will be accepted for backwards compatibility, all
+   * other values will be rejected with a 400 error.
    */
   top_p?: number;
 }
diff --git a/tests/api-resources/beta/messages/messages.test.ts b/tests/api-resources/beta/messages/messages.test.ts
@@ -120,7 +120,7 @@ describe('resource messages', () => {
   test('countTokens: only required params', async () => {
     const responsePromise = client.beta.messages.countTokens({
       messages: [{ content: 'string', role: 'user' }],
-      model: 'claude-opus-4-6',
+      model: 'claude-mythos-preview',
     });
     const rawResponse = await responsePromise.asResponse();
     expect(rawResponse).toBeInstanceOf(Response);
@@ -134,7 +134,7 @@ describe('resource messages', () => {
   test('countTokens: required and optional params', async () => {
     const response = await client.beta.messages.countTokens({
       messages: [{ content: 'string', role: 'user' }],
-      model: 'claude-opus-4-6',
+      model: 'claude-mythos-preview',
       cache_control: { type: 'ephemeral', ttl: '5m' },
       context_management: {
         edits: [
diff --git a/tests/api-resources/completions.test.ts b/tests/api-resources/completions.test.ts
@@ -11,7 +11,7 @@ describe('resource completions', () => {
   test('create: only required params', async () => {
     const responsePromise = client.completions.create({
       max_tokens_to_sample: 256,
-      model: 'claude-opus-4-6',
+      model: 'claude-mythos-preview',
       prompt: '\n\nHuman: Hello, world!\n\nAssistant:',
     });
     const rawResponse = await responsePromise.asResponse();
@@ -26,7 +26,7 @@ describe('resource completions', () => {
   test('create: required and optional params', async () => {
     const response = await client.completions.create({
       max_tokens_to_sample: 256,
-      model: 'claude-opus-4-6',
+      model: 'claude-mythos-preview',
       prompt: '\n\nHuman: Hello, world!\n\nAssistant:',
       metadata: { user_id: '13803d75-b4b5-4c3e-b2a2-6f21399b021b' },
       stop_sequences: ['string'],
diff --git a/tests/api-resources/messages/messages.test.ts b/tests/api-resources/messages/messages.test.ts
@@ -88,7 +88,7 @@ describe('resource messages', () => {
   test('countTokens: only required params', async () => {
     const responsePromise = client.messages.countTokens({
       messages: [{ content: 'string', role: 'user' }],
-      model: 'claude-opus-4-6',
+      model: 'claude-mythos-preview',
     });
     const rawResponse = await responsePromise.asResponse();
     expect(rawResponse).toBeInstanceOf(Response);
@@ -102,7 +102,7 @@ describe('resource messages', () => {
   test('countTokens: required and optional params', async () => {
     const response = await client.messages.countTokens({
       messages: [{ content: 'string', role: 'user' }],
-      model: 'claude-opus-4-6',
+      model: 'claude-mythos-preview',
       cache_control: { type: 'ephemeral', ttl: '5m' },
       output_config: {
         effort: 'low',
