npm install @anthropic-ai/claude-agent-sdk

import binPath from "@anthropic-ai/claude-agent-sdk-darwin-arm64/claude" with { type: "file" };
import { extractFromBunfs } from "@anthropic-ai/claude-agent-sdk/extract";
import { query } from "@anthropic-ai/claude-agent-sdk";

const cliPath = extractFromBunfs(binPath);

for await (const message of query({
  prompt: "Hello",
  options: { pathToClaudeCodeExecutable: cliPath },
})) {
  console.log(message);
}

function query({
  prompt,
  options
}: {
  prompt: string | AsyncIterable<SDKUserMessage>;
  options?: Options;
}): Query;

function startup(params?: {
  options?: Options;
  initializeTimeoutMs?: number;
}): Promise<WarmQuery>;

import { startup } from "@anthropic-ai/claude-agent-sdk";

// Pay startup cost upfront
const warm = await startup({ options: { maxTurns: 3 } });

// Later, when a prompt is ready, this is immediate
for await (const message of warm.query("What files are here?")) {
  console.log(message);
}

function prewarm(params?: {
  options?: Options;
  initializeTimeoutMs?: number;
}): Promise<SpareProcess>;

import { prewarm } from "@anthropic-ai/claude-agent-sdk";

// On application boot, before the session's folder is known
const spare = await prewarm({ options: { maxTurns: 3 } });

// Later, when the user starts a session in a folder
const claimedQuery = spare.claim({
  prompt: "What files are here?",
  options: { cwd: "/path/to/project" },
});

spare.claimed.catch((error: Error) => {
  // Unless the message starts with "option_not_applied", the prompt didn't run:
  // start this session with query() instead
  console.error("Claim failed:", error.message);
});

try {
  for await (const message of claimedQuery) {
    console.log(message);
  }
} catch (error) {
  // After a refused claim, the claimed query throws once it has yielded the error result
  console.error(`Session ended with an error: ${error}`);
}

function tool<Schema extends AnyZodRawShape>(
  name: string,
  description: string,
  inputSchema: Schema,
  handler: (args: InferShape<Schema>, extra: unknown) => Promise<CallToolResult>,
  extras?: { annotations?: ToolAnnotations; searchHint?: string; alwaysLoad?: boolean }
): SdkMcpToolDefinition<Schema>;

import { tool } from "@anthropic-ai/claude-agent-sdk";
import { z } from "zod";

const searchTool = tool(
  "search",
  "Search the web",
  { query: z.string() },
  async ({ query }) => {
    return { content: [{ type: "text", text: `Results for: ${query}` }] };
  },
  { annotations: { readOnlyHint: true, openWorldHint: true } }
);

function createSdkMcpServer(options: {
  name: string;
  version?: string;
  instructions?: string;
  tools?: Array<SdkMcpToolDefinition<any>>;
  alwaysLoad?: boolean;
  timeout?: number;
}): McpSdkServerConfigWithInstance;

function listSessions(options?: ListSessionsOptions): Promise<SDKSessionInfo[]>;

import { listSessions } from "@anthropic-ai/claude-agent-sdk";

const sessions = await listSessions({ dir: "/path/to/project", limit: 10 });

for (const session of sessions) {
  console.log(`${session.summary} (${session.sessionId})`);
}

function getSessionMessages(
  sessionId: string,
  options?: GetSessionMessagesOptions
): Promise<SessionMessage[]>;

import { listSessions, getSessionMessages } from "@anthropic-ai/claude-agent-sdk";

const [latest] = await listSessions({ dir: "/path/to/project", limit: 1 });

if (latest) {
  const messages = await getSessionMessages(latest.sessionId, {
    dir: "/path/to/project",
    limit: 20
  });

  for (const msg of messages) {
    console.log(`[${msg.type}] ${msg.uuid}`);
  }
}

function getSessionInfo(
  sessionId: string,
  options?: GetSessionInfoOptions
): Promise<SDKSessionInfo | undefined>;

function renameSession(
  sessionId: string,
  title: string,
  options?: SessionMutationOptions
): Promise<void>;

function tagSession(
  sessionId: string,
  tag: string | null,
  options?: SessionMutationOptions
): Promise<void>;

function forkSession(
  sessionId: string,
  options?: ForkSessionOptions
): Promise<ForkSessionResult>;

function resolveSettings(
  options?: ResolveSettingsOptions
): Promise<ResolvedSettings>;

import { resolveSettings } from "@anthropic-ai/claude-agent-sdk";

const { effective, provenance } = await resolveSettings({
  cwd: "/path/to/project",
  settingSources: ["user", "project", "local"],
});

console.log(`Cleanup period: ${effective.cleanupPeriodDays} days`);
console.log(`Set by: ${provenance.cleanupPeriodDays?.source}`);

import { query } from "@anthropic-ai/claude-agent-sdk";

const result = query({
  prompt: "Analyze this code",
  options: {
    env: {
      ...process.env,
      API_TIMEOUT_MS: "120000",
      CLAUDE_CODE_MAX_RETRIES: "2",
      CLAUDE_ASYNC_AGENT_STALL_TIMEOUT_MS: "120000",
    },
  },
});

interface Query extends AsyncGenerator<SDKMessage, void> {
  interrupt(): Promise<SDKControlInterruptResponse | undefined>;
  rewindFiles(
    userMessageId: string,
    options?: { dryRun?: boolean }
  ): Promise<RewindFilesResult>;
  setPermissionMode(mode: PermissionMode): Promise<void>;
  setModel(model?: string): Promise<void>;
  setMaxThinkingTokens(maxThinkingTokens: number | null): Promise<void>;
  applyFlagSettings(settings: {
    [K in keyof Settings]?: K extends 'effortLevel'
      ? 'low' | 'medium' | 'high' | 'xhigh' | 'max' | null
      : Settings[K] | null;
  }): Promise<void>;
  updateSettings(
    source: 'localSettings' | 'userSettings',
    settings: Record<string, unknown>,
  ): Promise<void>;
  initializationResult(): Promise<SDKControlInitializeResponse>;
  reinitialize(): Promise<SDKControlInitializeResponse>;
  supportedCommands(): Promise<SlashCommand[]>;
  supportedModels(): Promise<ModelInfo[]>;
  supportedAgents(): Promise<AgentInfo[]>;
  mcpServerStatus(): Promise<McpServerStatus[]>;
  getContextUsage(opts?: {
    detail?: 'summary' | 'full';
  }): Promise<SDKControlGetContextUsageResponse>;
  readFile(
    path: string,
    options?: { maxBytes?: number; encoding?: 'utf-8' | 'base64' }
  ): Promise<SDKControlReadFileResponse | null>;
  reloadPlugins(options?: {
    holdOnCacheImpact?: boolean;
    addPlugins?: SdkPluginConfig[];
  }): Promise<SDKControlReloadPluginsResponse>;
  reloadSkills(): Promise<SDKControlReloadSkillsResponse>;
  reloadOutputStyles(): Promise<SDKControlReloadOutputStylesResponse>;
  seedReadState(path: string, mtime: number): Promise<void>;
  accountInfo(): Promise<AccountInfo>;
  reconnectMcpServer(serverName: string): Promise<void>;
  toggleMcpServer(serverName: string, enabled: boolean): Promise<void>;
  setMcpServers(servers: Record<string, McpServerConfig>): Promise<McpSetServersResult>;
  setMcpPermissionModeOverride(
    serverName: string,
    mode: 'default' | 'auto' | null
  ): Promise<{ warning?: string }>;
  readMcpResource(serverName: string, uri: string): Promise<SDKControlMcpReadResourceResponse>;
  streamInput(stream: AsyncIterable<SDKUserMessage>): Promise<void>;
  stopTask(taskId: string): Promise<void>;
  backgroundTasks(toolUseId?: string): Promise<boolean>;
  close(): void;
}

import { query } from "@anthropic-ai/claude-agent-sdk";

const q = query({ prompt: messageStream });

// Override the model for the rest of the session
await q.applyFlagSettings({ model: "claude-opus-4-6" });

// Later: clear the override; the model resets to Claude Code's default
await q.applyFlagSettings({ model: null });

interface WarmQuery extends AsyncDisposable {
  query(prompt: string | AsyncIterable<SDKUserMessage>): Query;
  close(): void;
}

interface SpareProcess extends AsyncDisposable {
  claim(params: {
    prompt: string | AsyncIterable<SDKUserMessage>;
    options: ClaimOptions;
  }): Query;
  readonly claimed: Promise<{ cwd: string; sessionId: string; parkedMs?: number; sdkMcpSettled: boolean }>;
  readonly exited: Promise<void>;
  close(): void;
}

type SDKControlInitializeResponse = {
  commands: SlashCommand[];
  agents: AgentInfo[];
  output_style: string;
  available_output_styles: string[];
  models: ModelInfo[];
  account: AccountInfo;
  fast_mode_state?: "off" | "cooldown" | "on";
  fast_mode_disabled_reason?: FastModeDisabledReason;
  hooks_applied?: boolean;
  sdk_mcp_manifests_parked?: Record<
    string,
    | "parked"
    | "already_connected"
    | "protocol_version_mismatch"
    | "malformed"
    | "not_honoured"
  >;
  claude_code_version?: string;
};

type SDKControlInterruptResponse = {
  still_queued: string[];
  cancelled?: string[];
};

type SDKControlGetContextUsageResponse = {
  categories: {
    id?:
      | "system_prompt"
      | "system_tools"
      | "mcp_tools"
      | "mcp_instructions"
      | "mcp_tools_deferred"
      | "system_tools_deferred"
      | "custom_agents"
      | "memory_files"
      | "skills"
      | "messages"
      | "autocompact_buffer"
      | "compact_buffer"
      | "free_space";
    name: string;
    tokens: number;
    color: string;
    isDeferred?: boolean;
    kind: "used" | "free" | "buffer" | "deferred";
  }[];
  totalTokens: number;
  maxTokens: number;
  rawMaxTokens: number;
  percentage: number;
  gridRows: {
    color: string;
    isFilled: boolean;
    categoryName: string;
    tokens: number;
    percentage: number;
    squareFullness: number;
  }[][];
  model: string;
  memoryFiles: {
    path: string;
    type: string;
    tokens: number;
  }[];
  mcpTools: {
    name: string;
    serverName: string;
    tokens: number;
    isLoaded?: boolean;
  }[];
  mcpInstructions?: {
    serverName: string;
    tokens: number;
  }[];
  deferredBuiltinTools?: {
    name: string;
    tokens: number;
    isLoaded: boolean;
  }[];
  systemTools?: {
    name: string;
    tokens: number;
  }[];
  systemPromptSections?: {
    name: string;
    tokens: number;
  }[];
  agents: {
    agentType: string;
    source: string;
    pluginId?: string;
    path?: string;
    tokens: number;
  }[];
  slashCommands?: {
    totalCommands: number;
    includedCommands: number;
    tokens: number;
  };
  skills?: {
    totalSkills: number;
    includedSkills: number;
    tokens: number;
    skillFrontmatter: {
      name: string;
      source: string;
      pluginName?: string;
      pluginId?: string;
      path?: string;
      tokens: number;
    }[];
  };
  autoCompactThreshold?: number;
  isAutoCompactEnabled: boolean;
  messageBreakdown?: {
    toolCallTokens: number;
    toolResultTokens: number;
    attachmentTokens: number;
    assistantMessageTokens: number;
    userMessageTokens: number;
    redirectedContextTokens: number;
    unattributedTokens: number;
    toolCallsByType: {
      name: string;
      callTokens: number;
      resultTokens: number;
    }[];
    attachmentsByType: {
      name: string;
      tokens: number;
    }[];
  };
  apiUsage: {
    input_tokens: number;
    output_tokens: number;
    cache_creation_input_tokens: number;
    cache_read_input_tokens: number;
  } | null;
};

// q is the Query object that query() returned
const usage = await q.getContextUsage();
// undefined if no connected server supplies instructions
const row = usage.categories.find((c) => c.id === "mcp_instructions");

type SDKControlReadFileResponse = {
  contents: string;
  absPath: string;
  truncated?: boolean;
  encoding?: 'base64';
};

type SDKControlReloadPluginsResponse = {
  commands: SlashCommand[];
  agents: AgentInfo[];
  plugins: {
    name: string;
    path: string;
    source?: string;
    version?: string;
  }[];
  mcpServers: McpServerStatus[];
  error_count: number;
  held?: boolean;
  cache_impact?: {
    mcp_servers_added: string[];
    mcp_servers_removed: string[];
    lsp_tool_change: ("adds" | "may-add" | "removes" | "may-remove") | null;
  };
};

const result = await q.reloadPlugins({
  addPlugins: [{ type: "local", path: "/opt/my-app/plugins/reports" }]
});

console.log(result.plugins.map((plugin) => plugin.path));

type SDKControlReloadSkillsResponse = {
  skills: SlashCommand[];
};

type SDKControlReloadOutputStylesResponse = {
  available_output_styles: string[];
};

type SDKControlMcpReadResourceResponse = {
  contents: {
    uri: string;
    mimeType?: string;
    text?: string;
    blob?: string;
    _meta?: Record<string, unknown>;
  }[];
};

type AgentDefinition = {
  description: string;
  tools?: string[];
  disallowedTools?: string[];
  prompt: string;
  model?: string;
  mcpServers?: AgentMcpServerSpec[];
  skills?: string[];
  initialPrompt?: string;
  maxTurns?: number;
  autoCompactWindow?: number;
  background?: boolean;
  omitClaudeMd?: boolean;
  memory?: "user" | "project" | "local";
  effort?: "low" | "medium" | "high" | "xhigh" | "max" | number;
  permissionMode?: PermissionMode;
  criticalSystemReminder_EXPERIMENTAL?: string;
};

type AgentMcpServerSpec = string | Record<string, McpServerConfigForProcessTransport>;

type SettingSource = "user" | "project" | "local";

import { query } from "@anthropic-ai/claude-agent-sdk";

// Do not load user, project, or local settings from disk
const result = query({
  prompt: "Analyze this code",
  options: { settingSources: [] }
});

import { query } from "@anthropic-ai/claude-agent-sdk";

// Load only project settings, ignore user and local
const result = query({
  prompt: "Run CI checks",
  options: {
    settingSources: ["project"] // Only .claude/settings.json
  }
});

type PermissionMode =
  | "default" // Standard permission behavior
  | "acceptEdits" // Auto-accept file edits
  | "bypassPermissions" // Bypass permission checks; explicit ask rules still prompt
  | "plan" // Planning mode - explore without editing
  | "dontAsk" // Don't prompt for permissions, deny if not pre-approved
  | "auto"; // A model classifier reviews actions such as shell commands and network requests

type CanUseTool = (
  toolName: string,
  input: Record<string, unknown>,
  options: {
    signal: AbortSignal;
    suggestions?: PermissionUpdate[];
    blockedPath?: string;
    mcpServer?: { name: string; source: string };
    decisionReason?: string;
    defaultToNo?: boolean;
    suppressAlwaysAllowRule?: boolean;
    toolUseID: string;
    agentID?: string;
    requestId: string;
  }
) => Promise<PermissionResult | null>;

type PermissionResult =
  | {
      behavior: "allow";
      updatedInput?: Record<string, unknown>;
      updatedPermissions?: PermissionUpdate[];
      toolUseID?: string;
    }
  | {
      behavior: "deny";
      message: string;
      interrupt?: boolean;
      toolUseID?: string;
    };

type ToolConfig = {
  askUserQuestion?: {
    previewFormat?: "markdown" | "html";
  };
};

type McpServerConfig =
  | McpStdioServerConfig
  | McpSSEServerConfig
  | McpHttpServerConfig
  | McpSdkServerConfigWithInstance;

type McpStdioServerConfig = {
  type?: "stdio";
  command: string;
  args?: string[];
  env?: Record<string, string>;
};

type McpSSEServerConfig = {
  type: "sse";
  url: string;
  headers?: Record<string, string>;
};

type McpHttpServerConfig = {
  type: "http";
  url: string;
  headers?: Record<string, string>;
};

type McpSdkServerConfigWithInstance = {
  type: "sdk";
  name: string;
  timeout?: number;
  tools?: McpServerToolPolicy[];
  instance: McpServer;
};

import { query, tool, createSdkMcpServer } from "@anthropic-ai/claude-agent-sdk";
import { z } from "zod";

const deleteRecord = tool(
  "delete_record",
  "Delete a customer record by ID",
  { id: z.string() },
  async ({ id }) => ({ content: [{ type: "text", text: `Deleted record ${id}` }] }),
  { annotations: { destructiveHint: true } }
);

const records = createSdkMcpServer({ name: "records", tools: [deleteRecord] });

for await (const message of query({
  prompt: "Delete customer record 42",
  options: {
    mcpServers: {
      // Spread the returned config and add the policy list beside it
      records: {
        ...records,
        tools: [{ name: "delete_record", permission_policy: "always_ask" as const }]
      }
    },
    allowedTools: ["mcp__records__*"],
    canUseTool: async (toolName, input) => {
      console.log(`Approval requested for ${toolName}`);
      return { behavior: "allow", updatedInput: input };
    }
  }
})) {
  if (message.type === "result" && message.subtype === "success") {
    console.log(message.result);
  }
}

type McpServerToolPolicy = {
  name: string;
  permission_policy?: "always_allow" | "always_ask" | "always_deny";
  org_max_permission?: "allow" | "ask" | "blocked";
};

type McpClaudeAIProxyServerConfig = {
  type: "claudeai-proxy";
  url: string;
  id: string;
};

type SdkPluginConfig = {
  type: "local";
  path: string;
  skipMcpDiscovery?: boolean;
};

plugins: [
  { type: "local", path: "./my-plugin" },
  { type: "local", path: "/absolute/path/to/plugin" }
];