From 61d1a70e6af2ff3c1c0f16517bca200f162cf9c1 Mon Sep 17 00:00:00 2001
From: "stainless-app[bot]"
 <142633134+stainless-app[bot]@users.noreply.github.com>
Date: Tue, 3 Mar 2026 14:16:43 +0000
Subject: [PATCH 1/4] chore(internal): codegen related update

---
 packages/mcp-server/package.json              |  6 +-
 packages/mcp-server/src/code-tool.ts          | 23 +++++-
 packages/mcp-server/src/docs-search-tool.ts   | 30 +++++++-
 packages/mcp-server/src/http.ts               | 74 +++++++++++++------
 packages/mcp-server/src/index.ts              | 26 ++++---
 packages/mcp-server/src/instructions.ts       |  3 +-
 packages/mcp-server/src/logger.ts             | 28 +++++++
 packages/mcp-server/src/options.ts            | 11 +++
 packages/mcp-server/src/stdio.ts              |  3 +-
 src/client.ts                                 |  6 ++
 .../classifications/universal/universal.ts    |  3 +
 src/resources/embeddings.ts                   |  3 +
 src/resources/extractions/qa/qa.ts            |  3 +
 src/resources/rerankings.ts                   |  3 +
 14 files changed, 179 insertions(+), 43 deletions(-)
 create mode 100644 packages/mcp-server/src/logger.ts

diff --git a/packages/mcp-server/package.json b/packages/mcp-server/package.json
index bc30dc0..6092466 100644
--- a/packages/mcp-server/package.json
+++ b/packages/mcp-server/package.json
@@ -39,8 +39,9 @@
     "express": "^5.1.0",
     "fuse.js": "^7.1.0",
     "jq-web": "https://github.com/stainless-api/jq-web/releases/download/v0.8.8/jq-web.tar.gz",
-    "morgan": "^1.10.0",
-    "morgan-body": "^2.6.9",
+    "pino": "^10.3.1",
+    "pino-http": "^11.0.0",
+    "pino-pretty": "^13.1.3",
     "qs": "^6.14.1",
     "typescript": "5.8.3",
     "yargs": "^17.7.2",
@@ -57,7 +58,6 @@
     "@types/cors": "^2.8.19",
     "@types/express": "^5.0.3",
     "@types/jest": "^29.4.0",
-    "@types/morgan": "^1.9.10",
     "@types/qs": "^6.14.0",
     "@types/yargs": "^17.0.8",
     "@typescript-eslint/eslint-plugin": "8.31.1",
diff --git a/packages/mcp-server/src/code-tool.ts b/packages/mcp-server/src/code-tool.ts
index 200bdd6..0d0d28d 100644
--- a/packages/mcp-server/src/code-tool.ts
+++ b/packages/mcp-server/src/code-tool.ts
@@ -17,6 +17,7 @@ import {
 import { Tool } from '@modelcontextprotocol/sdk/types.js';
 import { readEnv, requireValue } from './util';
 import { WorkerInput, WorkerOutput } from './code-tool-types';
+import { getLogger } from './logger';
 import { SdkMethod } from './methods';
 import { McpCodeExecutionMode } from './options';
 import { ClientOptions } from 'isaacus';
@@ -87,6 +88,8 @@ export function codeTool({
     },
   };
 
+  const logger = getLogger();
+
   const handler = async ({
     reqContext,
     args,
@@ -111,11 +114,27 @@ export function codeTool({
       }
     }
 
+    let result: ToolCallResult;
+    const startTime = Date.now();
+
     if (codeExecutionMode === 'local') {
-      return await localDenoHandler({ reqContext, args });
+      logger.debug('Executing code in local Deno environment');
+      result = await localDenoHandler({ reqContext, args });
     } else {
-      return await remoteStainlessHandler({ reqContext, args });
+      logger.debug('Executing code in remote Stainless environment');
+      result = await remoteStainlessHandler({ reqContext, args });
     }
+
+    logger.info(
+      {
+        codeExecutionMode,
+        durationMs: Date.now() - startTime,
+        isError: result.isError,
+        contentRows: result.content?.length ?? 0,
+      },
+      'Got code tool execution result',
+    );
+    return result;
   };
 
   return { metadata, tool, handler };
diff --git a/packages/mcp-server/src/docs-search-tool.ts b/packages/mcp-server/src/docs-search-tool.ts
index fa32550..ba77b72 100644
--- a/packages/mcp-server/src/docs-search-tool.ts
+++ b/packages/mcp-server/src/docs-search-tool.ts
@@ -1,7 +1,8 @@
 // File generated from our OpenAPI spec by Stainless. See CONTRIBUTING.md for details.
 
-import { Metadata, McpRequestContext, asTextContentResult } from './types';
 import { Tool } from '@modelcontextprotocol/sdk/types.js';
+import { Metadata, McpRequestContext, asTextContentResult } from './types';
+import { getLogger } from './logger';
 
 export const metadata: Metadata = {
   resource: 'all',
@@ -50,19 +51,42 @@ export const handler = async ({
 }) => {
   const body = args as any;
   const query = new URLSearchParams(body).toString();
+
+  const startTime = Date.now();
   const result = await fetch(`${docsSearchURL}?${query}`, {
     headers: {
       ...(reqContext.stainlessApiKey && { Authorization: reqContext.stainlessApiKey }),
     },
   });
 
+  const logger = getLogger();
+
   if (!result.ok) {
+    const errorText = await result.text();
+    logger.warn(
+      {
+        durationMs: Date.now() - startTime,
+        query: body.query,
+        status: result.status,
+        statusText: result.statusText,
+        errorText,
+      },
+      'Got error response from docs search tool',
+    );
     throw new Error(
-      `${result.status}: ${result.statusText} when using doc search tool. Details: ${await result.text()}`,
+      `${result.status}: ${result.statusText} when using doc search tool. Details: ${errorText}`,
     );
   }
 
-  return asTextContentResult(await result.json());
+  const resultBody = await result.json();
+  logger.info(
+    {
+      durationMs: Date.now() - startTime,
+      query: body.query,
+    },
+    'Got docs search result',
+  );
+  return asTextContentResult(resultBody);
 };
 
 export default { metadata, tool, handler };
diff --git a/packages/mcp-server/src/http.ts b/packages/mcp-server/src/http.ts
index 2d506d9..9606565 100644
--- a/packages/mcp-server/src/http.ts
+++ b/packages/mcp-server/src/http.ts
@@ -4,9 +4,10 @@ import { McpServer } from '@modelcontextprotocol/sdk/server/mcp';
 import { StreamableHTTPServerTransport } from '@modelcontextprotocol/sdk/server/streamableHttp.js';
 import { ClientOptions } from 'isaacus';
 import express from 'express';
-import morgan from 'morgan';
-import morganBody from 'morgan-body';
+import pino from 'pino';
+import pinoHttp from 'pino-http';
 import { getStainlessApiKey, parseClientAuthHeaders } from './auth';
+import { getLogger } from './logger';
 import { McpOptions } from './options';
 import { initMcpServer, newMcpServer } from './server';
 
@@ -70,29 +71,60 @@ const del = async (req: express.Request, res: express.Response) => {
   });
 };
 
+const redactHeaders = (headers: Record<string, any>) => {
+  const hiddenHeaders = /auth|cookie|key|token/i;
+  const filtered = { ...headers };
+  Object.keys(filtered).forEach((key) => {
+    if (hiddenHeaders.test(key)) {
+      filtered[key] = '[REDACTED]';
+    }
+  });
+  return filtered;
+};
+
 export const streamableHTTPApp = ({
   clientOptions = {},
   mcpOptions,
-  debug,
 }: {
   clientOptions?: ClientOptions;
   mcpOptions: McpOptions;
-  debug: boolean;
 }): express.Express => {
   const app = express();
   app.set('query parser', 'extended');
   app.use(express.json());
-
-  if (debug) {
-    morganBody(app, {
-      logAllReqHeader: true,
-      logAllResHeader: true,
-      logRequestBody: true,
-      logResponseBody: true,
-    });
-  } else {
-    app.use(morgan('combined'));
-  }
+  app.use(
+    pinoHttp({
+      logger: getLogger(),
+      customLogLevel: (req, res) => {
+        if (res.statusCode >= 500) {
+          return 'error';
+        } else if (res.statusCode >= 400) {
+          return 'warn';
+        }
+        return 'info';
+      },
+      customSuccessMessage: function (req, res) {
+        return `Request ${req.method} to ${req.url} completed with status ${res.statusCode}`;
+      },
+      customErrorMessage: function (req, res, err) {
+        return `Request ${req.method} to ${req.url} errored with status ${res.statusCode}`;
+      },
+      serializers: {
+        req: pino.stdSerializers.wrapRequestSerializer((req) => {
+          return {
+            ...req,
+            headers: redactHeaders(req.raw.headers),
+          };
+        }),
+        res: pino.stdSerializers.wrapResponseSerializer((res) => {
+          return {
+            ...res,
+            headers: redactHeaders(res.headers),
+          };
+        }),
+      },
+    }),
+  );
 
   app.get('/health', async (req: express.Request, res: express.Response) => {
     res.status(200).send('OK');
@@ -106,22 +138,22 @@ export const streamableHTTPApp = ({
 
 export const launchStreamableHTTPServer = async ({
   mcpOptions,
-  debug,
   port,
 }: {
   mcpOptions: McpOptions;
-  debug: boolean;
   port: number | string | undefined;
 }) => {
-  const app = streamableHTTPApp({ mcpOptions, debug });
+  const app = streamableHTTPApp({ mcpOptions });
   const server = app.listen(port);
   const address = server.address();
 
+  const logger = getLogger();
+
   if (typeof address === 'string') {
-    console.error(`MCP Server running on streamable HTTP at ${address}`);
+    logger.info(`MCP Server running on streamable HTTP at ${address}`);
   } else if (address !== null) {
-    console.error(`MCP Server running on streamable HTTP on port ${address.port}`);
+    logger.info(`MCP Server running on streamable HTTP on port ${address.port}`);
   } else {
-    console.error(`MCP Server running on streamable HTTP on port ${port}`);
+    logger.info(`MCP Server running on streamable HTTP on port ${port}`);
   }
 };
diff --git a/packages/mcp-server/src/index.ts b/packages/mcp-server/src/index.ts
index 654d25c..5bca4a6 100644
--- a/packages/mcp-server/src/index.ts
+++ b/packages/mcp-server/src/index.ts
@@ -5,15 +5,20 @@ import { McpOptions, parseCLIOptions } from './options';
 import { launchStdioServer } from './stdio';
 import { launchStreamableHTTPServer } from './http';
 import type { McpTool } from './types';
+import { configureLogger, getLogger } from './logger';
 
 async function main() {
   const options = parseOptionsOrError();
+  configureLogger({
+    level: options.debug ? 'debug' : 'info',
+    pretty: options.logFormat === 'pretty',
+  });
 
   const selectedTools = await selectToolsOrError(options);
 
-  console.error(
-    `MCP Server starting with ${selectedTools.length} tools:`,
-    selectedTools.map((e) => e.tool.name),
+  getLogger().info(
+    { tools: selectedTools.map((e) => e.tool.name) },
+    `MCP Server starting with ${selectedTools.length} tools`,
   );
 
   switch (options.transport) {
@@ -23,7 +28,6 @@ async function main() {
     case 'http':
       await launchStreamableHTTPServer({
         mcpOptions: options,
-        debug: options.debug,
         port: options.socket ?? options.port,
       });
       break;
@@ -32,7 +36,8 @@ async function main() {
 
 if (require.main === module) {
   main().catch((error) => {
-    console.error('Fatal error in main():', error);
+    // Logger might not be initialized yet
+    console.error('Fatal error in main()', error);
     process.exit(1);
   });
 }
@@ -41,7 +46,8 @@ function parseOptionsOrError() {
   try {
     return parseCLIOptions();
   } catch (error) {
-    console.error('Error parsing options:', error);
+    // Logger is initialized after options, so use console.error here
+    console.error('Error parsing options', error);
     process.exit(1);
   }
 }
@@ -50,16 +56,12 @@ async function selectToolsOrError(options: McpOptions): Promise<McpTool[]> {
   try {
     const includedTools = selectTools(options);
     if (includedTools.length === 0) {
-      console.error('No tools match the provided filters.');
+      getLogger().error('No tools match the provided filters');
       process.exit(1);
     }
     return includedTools;
   } catch (error) {
-    if (error instanceof Error) {
-      console.error('Error filtering tools:', error.message);
-    } else {
-      console.error('Error filtering tools:', error);
-    }
+    getLogger().error({ error }, 'Error filtering tools');
     process.exit(1);
   }
 }
diff --git a/packages/mcp-server/src/instructions.ts b/packages/mcp-server/src/instructions.ts
index 229beb7..c047841 100644
--- a/packages/mcp-server/src/instructions.ts
+++ b/packages/mcp-server/src/instructions.ts
@@ -1,6 +1,7 @@
 // File generated from our OpenAPI spec by Stainless. See CONTRIBUTING.md for details.
 
 import { readEnv } from './util';
+import { getLogger } from './logger';
 
 const INSTRUCTIONS_CACHE_TTL_MS = 15 * 60 * 1000; // 15 minutes
 
@@ -50,7 +51,7 @@ async function fetchLatestInstructions(stainlessApiKey: string | undefined): Pro
 
   let instructions: string | undefined;
   if (!response.ok) {
-    console.warn(
+    getLogger().warn(
       'Warning: failed to retrieve MCP server instructions. Proceeding with default instructions...',
     );
 
diff --git a/packages/mcp-server/src/logger.ts b/packages/mcp-server/src/logger.ts
new file mode 100644
index 0000000..29dab11
--- /dev/null
+++ b/packages/mcp-server/src/logger.ts
@@ -0,0 +1,28 @@
+// File generated from our OpenAPI spec by Stainless. See CONTRIBUTING.md for details.
+
+import { pino, type Level, type Logger } from 'pino';
+import pretty from 'pino-pretty';
+
+let _logger: Logger | undefined;
+
+export function configureLogger({ level, pretty: usePretty }: { level: Level; pretty: boolean }): void {
+  _logger = pino(
+    {
+      level,
+      timestamp: pino.stdTimeFunctions.isoTime,
+      formatters: {
+        level(label) {
+          return { level: label };
+        },
+      },
+    },
+    usePretty ? pretty({ colorize: true, levelFirst: true, destination: 2 }) : process.stderr,
+  );
+}
+
+export function getLogger(): Logger {
+  if (!_logger) {
+    throw new Error('Logger has not been configured. Call configureLogger() before using the logger.');
+  }
+  return _logger;
+}
diff --git a/packages/mcp-server/src/options.ts b/packages/mcp-server/src/options.ts
index 069b881..b9e8e8a 100644
--- a/packages/mcp-server/src/options.ts
+++ b/packages/mcp-server/src/options.ts
@@ -8,6 +8,7 @@ import { readEnv } from './util';
 
 export type CLIOptions = McpOptions & {
   debug: boolean;
+  logFormat: 'json' | 'pretty';
   transport: 'stdio' | 'http';
   port: number | undefined;
   socket: string | undefined;
@@ -52,6 +53,11 @@ export function parseCLIOptions(): CLIOptions {
         "Where to run code execution in code tool; 'stainless-sandbox' will execute code in Stainless-hosted sandboxes whereas 'local' will execute code locally on the MCP server machine.",
     })
     .option('debug', { type: 'boolean', description: 'Enable debug logging' })
+    .option('log-format', {
+      type: 'string',
+      choices: ['json', 'pretty'],
+      description: 'Format for log output; defaults to json unless tty is detected',
+    })
     .option('no-tools', {
       type: 'string',
       array: true,
@@ -97,6 +103,10 @@ export function parseCLIOptions(): CLIOptions {
   const includeDocsTools = shouldIncludeToolType('docs');
 
   const transport = argv.transport as 'stdio' | 'http';
+  const logFormat =
+    argv.logFormat ? (argv.logFormat as 'json' | 'pretty')
+    : process.stderr.isTTY ? 'pretty'
+    : 'json';
 
   return {
     ...(includeCodeTool !== undefined && { includeCodeTool }),
@@ -108,6 +118,7 @@ export function parseCLIOptions(): CLIOptions {
     codeBlockedMethods: argv.codeBlockedMethods,
     codeExecutionMode: argv.codeExecutionMode as McpCodeExecutionMode,
     transport,
+    logFormat,
     port: argv.port,
     socket: argv.socket,
   };
diff --git a/packages/mcp-server/src/stdio.ts b/packages/mcp-server/src/stdio.ts
index ceccaed..e8bcbb1 100644
--- a/packages/mcp-server/src/stdio.ts
+++ b/packages/mcp-server/src/stdio.ts
@@ -1,6 +1,7 @@
 import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js';
 import { McpOptions } from './options';
 import { initMcpServer, newMcpServer } from './server';
+import { getLogger } from './logger';
 
 export const launchStdioServer = async (mcpOptions: McpOptions) => {
   const server = await newMcpServer(mcpOptions.stainlessApiKey);
@@ -9,5 +10,5 @@ export const launchStdioServer = async (mcpOptions: McpOptions) => {
 
   const transport = new StdioServerTransport();
   await server.connect(transport);
-  console.error('MCP Server running on stdio');
+  getLogger().info('MCP Server running on stdio');
 };
diff --git a/src/client.ts b/src/client.ts
index 2713576..29f625d 100644
--- a/src/client.ts
+++ b/src/client.ts
@@ -722,8 +722,14 @@ export class Isaacus {
 
   static toFile = Uploads.toFile;
 
+  /**
+   * Embed legal texts with Isaacus legal AI embedders.
+   */
   embeddings: API.Embeddings = new API.Embeddings(this);
   classifications: API.Classifications = new API.Classifications(this);
+  /**
+   * Rerank legal documents by their relevance to queries with Isaacus legal AI rerankers.
+   */
   rerankings: API.Rerankings = new API.Rerankings(this);
   extractions: API.Extractions = new API.Extractions(this);
   enrichments: API.Enrichments = new API.Enrichments(this);
diff --git a/src/resources/classifications/universal/universal.ts b/src/resources/classifications/universal/universal.ts
index b0fded3..a022a4d 100644
--- a/src/resources/classifications/universal/universal.ts
+++ b/src/resources/classifications/universal/universal.ts
@@ -4,6 +4,9 @@ import { APIResource } from '../../../core/resource';
 import { APIPromise } from '../../../core/api-promise';
 import { RequestOptions } from '../../../internal/request-options';
 
+/**
+ * Classify legal documents with Isaacus legal AI classifiers.
+ */
 export class Universal extends APIResource {
   /**
    * Classify the relevance of legal documents to a query with an Isaacus universal
diff --git a/src/resources/embeddings.ts b/src/resources/embeddings.ts
index 01dd6ea..e76d31a 100644
--- a/src/resources/embeddings.ts
+++ b/src/resources/embeddings.ts
@@ -4,6 +4,9 @@ import { APIResource } from '../core/resource';
 import { APIPromise } from '../core/api-promise';
 import { RequestOptions } from '../internal/request-options';
 
+/**
+ * Embed legal texts with Isaacus legal AI embedders.
+ */
 export class Embeddings extends APIResource {
   /**
    * Embed legal texts with an Isaacus legal AI embedder.
diff --git a/src/resources/extractions/qa/qa.ts b/src/resources/extractions/qa/qa.ts
index 873bf33..2934cb2 100644
--- a/src/resources/extractions/qa/qa.ts
+++ b/src/resources/extractions/qa/qa.ts
@@ -4,6 +4,9 @@ import { APIResource } from '../../../core/resource';
 import { APIPromise } from '../../../core/api-promise';
 import { RequestOptions } from '../../../internal/request-options';
 
+/**
+ * Extract information from legal documents with Isaacus legal AI extractors.
+ */
 export class QA extends APIResource {
   /**
    * Extract answers to questions from legal documents with an Isaacus legal AI
diff --git a/src/resources/rerankings.ts b/src/resources/rerankings.ts
index 9e7e84e..a84c3f8 100644
--- a/src/resources/rerankings.ts
+++ b/src/resources/rerankings.ts
@@ -4,6 +4,9 @@ import { APIResource } from '../core/resource';
 import { APIPromise } from '../core/api-promise';
 import { RequestOptions } from '../internal/request-options';
 
+/**
+ * Rerank legal documents by their relevance to queries with Isaacus legal AI rerankers.
+ */
 export class Rerankings extends APIResource {
   /**
    * Rank legal documents by their relevance to a query with an Isaacus legal AI

From 8d188e6a165648c20580f15c5f4ce8febc7acab1 Mon Sep 17 00:00:00 2001
From: "stainless-app[bot]"
 <142633134+stainless-app[bot]@users.noreply.github.com>
Date: Tue, 3 Mar 2026 15:00:18 +0000
Subject: [PATCH 2/4] chore(mcp-server): return access instructions for 404
 without API key

---
 packages/mcp-server/src/code-tool.ts        | 5 +++++
 packages/mcp-server/src/docs-search-tool.ts | 7 +++++++
 2 files changed, 12 insertions(+)

diff --git a/packages/mcp-server/src/code-tool.ts b/packages/mcp-server/src/code-tool.ts
index 0d0d28d..3e38f7b 100644
--- a/packages/mcp-server/src/code-tool.ts
+++ b/packages/mcp-server/src/code-tool.ts
@@ -176,6 +176,11 @@ const remoteStainlessHandler = async ({
   });
 
   if (!res.ok) {
+    if (res.status === 404 && !reqContext.stainlessApiKey) {
+      throw new Error(
+        'Could not access code tool for this project. You may need to provide a Stainless API key via the STAINLESS_API_KEY environment variable, the --stainless-api-key flag, or the x-stainless-api-key HTTP header.',
+      );
+    }
     throw new Error(
       `${res.status}: ${
         res.statusText
diff --git a/packages/mcp-server/src/docs-search-tool.ts b/packages/mcp-server/src/docs-search-tool.ts
index ba77b72..3b0d218 100644
--- a/packages/mcp-server/src/docs-search-tool.ts
+++ b/packages/mcp-server/src/docs-search-tool.ts
@@ -73,6 +73,13 @@ export const handler = async ({
       },
       'Got error response from docs search tool',
     );
+
+    if (result.status === 404 && !reqContext.stainlessApiKey) {
+      throw new Error(
+        'Could not find docs for this project. You may need to provide a Stainless API key via the STAINLESS_API_KEY environment variable, the --stainless-api-key flag, or the x-stainless-api-key HTTP header.',
+      );
+    }
+
     throw new Error(
       `${result.status}: ${result.statusText} when using doc search tool. Details: ${errorText}`,
     );

From e372066ae02d0ffcf5fae210ba027c9b13950141 Mon Sep 17 00:00:00 2001
From: "stainless-app[bot]"
 <142633134+stainless-app[bot]@users.noreply.github.com>
Date: Wed, 4 Mar 2026 23:34:18 +0000
Subject: [PATCH 3/4] chore(internal): use x-stainless-mcp-client-envs header
 for MCP remote code tool calls

---
 packages/mcp-server/src/code-tool.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/mcp-server/src/code-tool.ts b/packages/mcp-server/src/code-tool.ts
index 3e38f7b..6396cb7 100644
--- a/packages/mcp-server/src/code-tool.ts
+++ b/packages/mcp-server/src/code-tool.ts
@@ -159,7 +159,7 @@ const remoteStainlessHandler = async ({
     headers: {
       ...(reqContext.stainlessApiKey && { Authorization: reqContext.stainlessApiKey }),
       'Content-Type': 'application/json',
-      client_envs: JSON.stringify({
+      'x-stainless-mcp-client-envs': JSON.stringify({
         ISAACUS_API_KEY: requireValue(
           readEnv('ISAACUS_API_KEY') ?? client.apiKey,
           'set ISAACUS_API_KEY environment variable or provide apiKey client option',

From 9404ff18a42d1c4624b1e355c9177618a028c9c5 Mon Sep 17 00:00:00 2001
From: "stainless-app[bot]"
 <142633134+stainless-app[bot]@users.noreply.github.com>
Date: Wed, 4 Mar 2026 23:34:38 +0000
Subject: [PATCH 4/4] release: 0.21.1

---
 .release-please-manifest.json     |  2 +-
 CHANGELOG.md                      | 10 ++++++++++
 package.json                      |  2 +-
 packages/mcp-server/manifest.json |  2 +-
 packages/mcp-server/package.json  |  2 +-
 packages/mcp-server/src/server.ts |  2 +-
 src/version.ts                    |  2 +-
 7 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/.release-please-manifest.json b/.release-please-manifest.json
index d353515..727a5db 100644
--- a/.release-please-manifest.json
+++ b/.release-please-manifest.json
@@ -1,3 +1,3 @@
 {
-  ".": "0.21.0"
+  ".": "0.21.1"
 }
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 96084f7..29d0bf2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,15 @@
 # Changelog
 
+## 0.21.1 (2026-03-04)
+
+Full Changelog: [v0.21.0...v0.21.1](https://github.com/isaacus-dev/isaacus-typescript/compare/v0.21.0...v0.21.1)
+
+### Chores
+
+* **internal:** codegen related update ([61d1a70](https://github.com/isaacus-dev/isaacus-typescript/commit/61d1a70e6af2ff3c1c0f16517bca200f162cf9c1))
+* **internal:** use x-stainless-mcp-client-envs header for MCP remote code tool calls ([e372066](https://github.com/isaacus-dev/isaacus-typescript/commit/e372066ae02d0ffcf5fae210ba027c9b13950141))
+* **mcp-server:** return access instructions for 404 without API key ([8d188e6](https://github.com/isaacus-dev/isaacus-typescript/commit/8d188e6a165648c20580f15c5f4ce8febc7acab1))
+
 ## 0.21.0 (2026-03-03)
 
 Full Changelog: [v0.20.2...v0.21.0](https://github.com/isaacus-dev/isaacus-typescript/compare/v0.20.2...v0.21.0)
diff --git a/package.json b/package.json
index c74b97b..cf4c02c 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "isaacus",
-  "version": "0.21.0",
+  "version": "0.21.1",
   "description": "The official TypeScript library for the Isaacus API",
   "author": "Isaacus <support@isaacus.com>",
   "types": "dist/index.d.ts",
diff --git a/packages/mcp-server/manifest.json b/packages/mcp-server/manifest.json
index a5d6cf5..99a1b91 100644
--- a/packages/mcp-server/manifest.json
+++ b/packages/mcp-server/manifest.json
@@ -1,7 +1,7 @@
 {
   "dxt_version": "0.2",
   "name": "isaacus-mcp",
-  "version": "0.21.0",
+  "version": "0.21.1",
   "description": "The official MCP Server for the Isaacus API",
   "author": {
     "name": "Isaacus",
diff --git a/packages/mcp-server/package.json b/packages/mcp-server/package.json
index 6092466..4850528 100644
--- a/packages/mcp-server/package.json
+++ b/packages/mcp-server/package.json
@@ -1,6 +1,6 @@
 {
   "name": "isaacus-mcp",
-  "version": "0.21.0",
+  "version": "0.21.1",
   "description": "The official MCP Server for the Isaacus API",
   "author": "Isaacus <support@isaacus.com>",
   "types": "dist/index.d.ts",
diff --git a/packages/mcp-server/src/server.ts b/packages/mcp-server/src/server.ts
index 6fd947c..6d91fca 100644
--- a/packages/mcp-server/src/server.ts
+++ b/packages/mcp-server/src/server.ts
@@ -20,7 +20,7 @@ export const newMcpServer = async (stainlessApiKey: string | undefined) =>
   new McpServer(
     {
       name: 'isaacus_api',
-      version: '0.21.0',
+      version: '0.21.1',
     },
     {
       instructions: await getInstructions(stainlessApiKey),
diff --git a/src/version.ts b/src/version.ts
index bc95435..64a9ac6 100644
--- a/src/version.ts
+++ b/src/version.ts
@@ -1 +1 @@
-export const VERSION = '0.21.0'; // x-release-please-version
+export const VERSION = '0.21.1'; // x-release-please-version