Tool, Command, and Config Types

These are the types behind $.tool, $.command, and $.config. They describe a tool call, a permission check, a command run, and a row of the /config menu.

Pages

Page	What is in it
Command, Config, and Registered Tool Types	`BuiltinToolCallInput` to `RegisteredToolSpec`: built-in tool calls, command types, `/config` row types, and registered tool specs.
Tool Call, Check, and Describe Types	`ToolCallReserved` to `ToolUseSummary`: tool call results, permission checks, descriptions, envelopes, and summaries.

Example

The first call asks the permission system about a tool call. The second line reads the messages of a subagent that made a tool use.

const { decision } = await $.tool.check({ tool: "Read", input });
if (use.agentId) child = await $.session.messages({ agentId: use.agentId });

Types without Fields

These types are aliases, unions, or plain shapes. Each row gives its use and its shape.

Type	Status	What it is for	Shape and limits
`BuiltinToolInputs`	Documented: An official docs page names this item.	The arguments of each built-in tool by name, for declaration merging. It is empty until a declaration file adds entries. Then `e.tool === "Bash"` narrows `e` to the arguments of Bash.	Interface. The engine lays the set of this build beside a mod that it loads (claude-code-tools/index.d.ts), from the input schema of each tool.
`BuiltinToolName`	Documented: An official docs page names this item.	The names of the built-in tools.	Alias of `keyof BuiltinToolInputs & string`.
`BuiltinToolResults`	Documented: An official docs page names this item.	The structured result of each built-in tool by name, for declaration merging. It is empty until a declaration file adds entries. Then after `e.tool === "Bash"` the `result` of `next(e)` is the record of Bash.	Interface. The engine lays the set of this build beside a mod that it loads (claude-code-tools/index.d.ts), from the output schema of each tool. A tool without one is `unknown`.
`CommandDescribeResult`	Documented: An official docs page names this item.	What a `command.describe` hook returns: the description, hint and hidden flag that the menu uses. The name, `immediate` and `provider` stay as they were.	Alias of `Omit<CommandDescribeInput, 'command' \| 'immediate' \| 'provider'>`. Used by `command.describe`, `$.command.describe`.
`CommandSource`	Documented: An official docs page names this item.	Where a slash command comes from, as `$.command.list()` tells them apart.	Alias of `'builtin' \| 'plugin' \| 'user' \| 'mcp'`. `builtin` ships with Claude Code. `user` is the own file of the person or project.
`ConfigDescribeResult`	Documented: An official docs page names this item.	What a `config.describe` hook returns: the label, help text and hidden flag that the menu uses. The key and provider stay as they were.	Alias of `Omit<ConfigDescribeInput, 'key' \| 'provider'>`. Used by `config.describe`, `$.config.describe`.
`ConfigKind`	Documented: An official docs page names this item.	How a `/config` row takes its value: `boolean` toggles, `choice` picks one of its `options`, `text` takes a string, `number` a number.	Alias of `'boolean' \| 'choice' \| 'text' \| 'number'`.
`ConfigSetArgs`	Documented: An official docs page names this item.	The input of `config.set` as the `$.config.set(args)` of a plugin takes it: the key of the row and the value. The engine fills the rest.	Alias of `Pick<ConfigSetInput, 'key' \| 'value'>`. Used by `$.config.set`.
`ConfigValue`	Documented: An official docs page names this item.	The value of a `/config` row as a hook and `$.config` see it. It is a boolean (toggle), a string (choice or text), a number, or a list of strings.	Alias of `boolean \| string \| number \| readonly string[]`.
`ToolCallArgs`	Documented: An official docs page names this item.	The input of `tool.call` as the call takes it. `tool_use_id` and `agentId` may ride along (a hook that passes the input of its event on) and the call drops them.	Alias of `ToolCallEnvelope extends infer I ? I extends ToolCallEnvelope ? Omit<I, 'tool_use_id'> & ToolCallReserved<I['tool']> : never : never`. The run gets its own id and runs in the loop of the session.
`ToolCallEnvelope`	Documented: An official docs page names this item.	The envelope that the two tool events share. It has the tool, the id of this call, and the arguments of the tool spread beside them (`e.command` for Bash).	Alias of `BuiltinToolCallInput \| McpToolCallInput`. A union keyed by `tool`. After `if (e.tool === "Bash")`, `e.command` is a string.
`ToolCallInput`	Documented: An official docs page names this item.	The input of `tool.call`: the tool, the id of this call, the arguments of the tool beside them (`e.command` for Bash), and `agentId` in a subagent.	Alias of `ToolCallEnvelope & AgentLoop & ToolRequestMeta`. `tool`, `tool_use_id`, and `agentId` are reserved. A rewrite of any is refused. Used by `tool.call`.
`ToolCallOverloads`	Documented: An official docs page names this item.	`$.tool.call(input)`: resolves with `result` typed for the tool that `input` names (ToolCallResult), or loosely for an input that names none literally.	Alias of `{ <T extends string>(input: ToolCallArgs & ToolNamed<T>): Promise<ToolCallResult<T>>, (input: ToolCallArgs): Promise<ToolCallResult>, }`. Used by `$.tool.call`.
`ToolCheckArgs`	Documented: An official docs page names this item.	The input of `tool.check` as `$.tool.check` takes it: the tool and its arguments. The engine sets the id of the call, `agentId`, the ceiling, the approver, and `isReadOnly`.	Alias of `Pick<ToolCheckInput, 'tool' \| 'input'>`. Used by `$.tool.check`.
`ToolCheckApprover`	Documented: An official docs page names this item.	Who answers the asks of a `tool.check` evaluation: `host`, the program that answers a hosted session's asks or a served call's own session, or `person`, a dialog or a card the person answers (new in 2.1.307, replaces `ToolCheckDecider`).	Alias of `'host' \| 'person'`. Used by `ToolCheckInput.approver`.
`ToolCheckDecision`	Documented: An official docs page names this item.	The verdict of `tool.check`: run the tool, refuse it, or put it to a decider. The decider is the decider of the mode (the dialog, the auto-mode classifier, a headless host). For the ask of a hook, it is a person.	Alias of `'allow' \| 'ask' \| 'deny'`.
`ToolDeferral`	Documented: An official docs page names this item.	Where a `tool.describe` answer places the tool: `true` behind ToolSearch (its schema loads when the model asks for it), `false` in the list of the prompt.	Alias of `boolean`. Left out of an answer, the placement beneath stands.
`ToolResultOf`	Documented: An official docs page names this item.	The structured result of the tool named `Name`: its BuiltinToolResults entry for a built-in tool, else `unknown`.	Alias of the result type of a tool by name. `Agent` also allows a teammate or call record. `unknown` covers an MCP tool or an unknown name.

Pages​

Example​

Types without Fields​

Related Pages​

Pages

Example

Types without Fields

Related Pages