Quick Reference
Model Options
model
The Claude model to use.
Shortcuts:
fallbackModel
Model to use if primary model is unavailable or rate-limited.
Limit Options
maxTurns
Maximum number of conversation turns (user message + assistant response = 1 turn).
maxBudgetUsd
Maximum spend for this session in USD.
BudgetExceededError when exceeded.
maxThinkingTokens
Maximum tokens for Claude’s extended thinking (if enabled).
Prompt Options
systemPrompt
Instructions that guide Claude’s behavior. Can be a string or object.
String format:
Tool Options
tools
Array of tool definitions to make available to Claude.
mcpServers
Array of MCP server definitions containing multiple tools.
allowedTools
Whitelist of tool names Claude can use. If specified, only these tools are available.
disallowedTools
Blacklist of tool names Claude cannot use.
Session Management
sessionId
Resume an existing session by ID.
forkSession
Create a copy of an existing session instead of resuming it.
continue
Continue from where the previous session left off.
resumeSessionAt
Resume at a specific point in the conversation history.
settingSources
Configure which setting sources to load configuration from.
jobId
Job ID for tracking background/deferred executions (used with the /incubate API).
Output Options
outputFormat
Force structured output using JSON Schema.
includePartialMessages
Include partial (streaming) messages in the message history.
Environment Options
env
Environment variables available to tools in the sandbox.
permissionMode
How Claude handles permission requests for tools.
allowDangerouslySkipPermissions
Enable bypass of all permission checks. Use with caution.
betas
Enable beta features.
Agent Options
agents
Define sub-agents that Claude can delegate to.
Client Options
Options passed when creating theChuckyClient: