Module tool 

Module defining tool related structs and traits.

The Tool trait defines a simple interface for creating tools that can be used by Agents.

The ToolEmbedding trait extends the Tool trait to allow for tools that can be stored in a vector store and RAGged.

The ToolSet struct is a collection of tools that can be used by an Agent and optionally RAGged.

Structured tool results

A tool call resolves to a structured ToolExecutionResult — model-visible output, a machine-readable ToolOutcome (success, a classified ToolFailure, skipped, or denied), and ToolResultExtensions metadata that is never sent to the model. This is what flows to the StepEvent::ToolResult hook so a policy can steer on why a tool failed without parsing strings. A tool classifies its own error type via Tool::classify_error and can return richer outcomes/metadata via Tool::call_structured and ToolReturn.

Modules

builtin

Built-in tools shipped with rig that agents can use out of the box.

rmcprmcp

MCP (Model Context Protocol) integration via the rmcp crate.

server

Structs

MissingExtension

Error returned by ToolCallExtensions::require and ToolResultExtensions::require when the requested value is not present.

ToolCallExtensions

Per-call runtime extensions supplied to a tool by its caller.

ToolExecutionResult

The full structured result of a single tool execution.

ToolFailure

A structured, model-independent description of a tool execution failure.

ToolResultExtensions

Type-erased metadata a tool attaches to its structured result.

ToolReturn

A tool’s return value carrying an optional structured outcome and metadata.

ToolSet

A struct that holds a set of tools.

ToolSetBuilder

Builder for constructing a ToolSet with static and dynamic tools.

Enums

ToolError

ToolFailureKind

How a tool execution failed, as a closed set of standard kinds.

ToolOutcome

The structured outcome of a tool call: what happened, independent of the model-visible text.

ToolReturnOutcome

The outcome a tool declares for a call it executed.

ToolSetError

Traits

Tool

Trait that represents a simple LLM tool.

ToolDyn

Wrapper trait to allow for dynamic dispatch of simple tools.

ToolEmbedding

Trait that represents an LLM tool that can be stored in a vector store and RAGged

ToolEmbeddingDyn

Wrapper trait to allow for dynamic dispatch of raggable tools

Functions

tool_definition

Generate a provider-facing ToolDefinition from a registered tool’s flat metadata.