Tools overview

Capabilities that Claude can invoke on your behalf during a session — from reading files to searching the web to spawning sub-agents.

What are tools?

Tools are discrete capabilities that Claude invokes automatically while working on your task. When you give Claude a coding task it may read source files, run a build command, search for relevant code, and edit files — all via tools — without you having to issue each operation manually.

Each tool has:

• A name — a stable string identifier (e.g. Bash, Read, WebFetch)
• A description — plain-language explanation of what the tool does, used by Claude to decide when to invoke it
• A typed input schema — a JSON Schema defining every parameter, its type, whether it’s required, and any constraints

Claude selects which tool to call based on your task description and the current conversation context. It composes tool calls, waits for results, and continues reasoning — repeating until the task is complete or a turn limit is reached.

Permission prompts

Tools that have side effects (writing files, executing shell commands, fetching URLs) require your explicit permission before running. Claurst displays a prompt showing exactly what the tool is about to do; you can allow it once, allow it permanently for that tool/path, or deny it.

Read-only tools (file reads, glob/grep searches) are allowed automatically in Default mode.

Permission mode	Behavior
Default	Read-only operations auto-approved; write/execute operations prompt you
AcceptEdits	File writes auto-approved; shell execution still prompts
BypassPermissions	All operations auto-approved (use with caution)
Plan	Only read-only operations are permitted

BypassPermissions mode skips all confirmation prompts. Only use it in trusted, isolated environments.

How Claude discovers tools

The full tool list is large. To keep the initial prompt lean, most tools are deferred — hidden from the first request. Claude uses ToolSearch to discover deferred tools by keyword when it needs one. Tools marked alwaysLoad are always included in the initial context.

Complete tool reference

File tools

Tool	Description
Read	Read file contents with optional line offset and limit
Write	Create or overwrite a file
Edit	Exact string replacement inside an existing file
Glob	Find files by name pattern, sorted by modification time
Grep	Search file contents by regular expression (backed by ripgrep)
NotebookEdit	Edit cells in a Jupyter .ipynb notebook

Shell execution tools

Tool	Description
Bash	Execute shell commands with optional timeout and sandboxing
PowerShell	Windows PowerShell execution (mirrors Bash interface)

Web tools

Tool	Description
WebFetch	Fetch a URL and convert HTML to Markdown
WebSearch	Search the web; returns titles, URLs, and snippets

Agent & multi-agent tools

Tool	Description
Agent	Spawn a sub-agent with its own prompt and tool set (lives in cc-query)
SendMessage	Send a message to a named agent, broadcast (*), or a bridge session

Task management tools

Tool	Description
TaskCreate	Create a tracked background task with a subject and description
TaskGet	Retrieve a task’s status and details by ID
TaskUpdate	Update a task’s status, description, or dependency links
TaskList	List all non-deleted tasks
TaskStop	Stop a running task (sets status to Failed)
TaskOutput	Append output text to a task
TodoWrite	Replace the entire todo list atomically (legacy V1)

MCP integration tools

Tool	Description
mcp__<server>__<tool>	Invoke a tool provided by a connected MCP server
mcp__<server>__authenticate	Authenticate with an MCP server via OAuth
mcp__listResources	List resources available from connected MCP servers
ReadMcpResource	Read the contents of an MCP resource by URI

Plan mode tools

Tool	Description
EnterPlanMode	Switch to read-only planning mode
ExitPlanMode	Exit plan mode and optionally pre-approve specific commands

Scheduling tools

Tool	Description
CronCreate	Schedule a prompt to run on a cron expression
CronDelete	Cancel a scheduled job by ID
CronList	List all scheduled jobs

Worktree tools

Tool	Description
EnterWorktree	Create and switch to a git worktree for isolated work
ExitWorktree	Return from a worktree, keeping or removing it

Meta & discovery tools

Tool	Description
ToolSearch	Discover available tools by keyword or exact name lookup
AskUserQuestion	Prompt you for input during task execution
Skill	Invoke a user-defined skill (slash command macro)
Brief	Upload a file or message to the bridge session (KAIROS mode)
Sleep	Wait asynchronously without holding a shell process

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Explore by category

File tools

Read, write, edit, search, and manipulate files and notebooks.

Shell & web tools

Execute shell commands, fetch URLs, and search the web.

Agent & task tools

Spawn sub-agents, manage background tasks, schedule cron jobs, and coordinate agent swarms.