Crate ferrin_tool 

Ferrin tool system.

Tool definitions (Tool, ToolKind, ToolSet), the execution contract (ToolExecute, ToolOutput, ToolContext, ToolError), approval declarations (NeedsApproval), model-output normalisation, caller restrictions, tool fingerprints and (feature sandbox) the Sandbox trait with a local-process implementation.

Tool call parsing, approval resolution, execution scheduling and repair live in the core crate; this crate only describes tools and runs one execution when asked.

Design: docs/01-architecture/06-tool-system.md, ADR 0012.

Attribution

Portions of this crate are derived from the Vercel AI SDK (Apache-2.0, Copyright 2023 Vercel, Inc.), translated from TypeScript to Rust and modified. See the NOTICE file in the crate root.

Re-exports

pub use callers::PreparedToolCallers;

pub use callers::ToolCaller;

pub use callers::ToolCallerDefinition;

pub use callers::ToolCallers;

pub use fingerprint::ToolDrift;

pub use model_output::ErrorMode;

pub use sandbox::LocalProcessSandbox;

pub use sandbox::Sandbox;

pub use sandbox::SandboxProcess;

Modules

callers

Caller restrictions: which callers (the model directly, or other tools) may trigger a tool, and how caller tools receive their callees.

fingerprint

Tool fingerprints for drift detection.

model_output

Conversion of execution results into the output the model receives.

sandbox

Sandbox abstraction (feature sandbox): a session that reads and writes files and runs commands on behalf of tools.

Structs

DescriptionContext

Inputs available when resolving a dynamic description.

DuplicateToolError

A tool name was inserted twice into a crate::ToolSet.

ModelOutputArgs

Arguments of a ToModelOutputFn.

Schema

A JSON Schema paired with a function that validates a JSON value and converts it into T.

Tool

A tool definition. Built with Tool::function, Tool::dynamic, Tool::provider_defined or Tool::provider_executed.

ToolBuilder

Builds a Tool. I is the input type handed to the execute closure.

ToolContext

Per-call information handed to a tool execution.

ToolHooks

Lifecycle hooks around tool input.

ToolSet

Named tools available to a call. Insertion order is preserved; names are unique.

Enums

Description

Tool description sent to the model.

NeedsApproval

Tool-level approval declaration. Call-level approval policies configured on the generation take precedence over it.

ToolError

Error returned by a tool execution.

ToolKind

Who defines and who executes a tool.

ToolOutput

One output of a tool execution.

Traits

JsonSchema

A type which can be described as a JSON Schema document.

ToolExecute

Executes a tool.

Functions

execute_to_completion

Drives an output stream to its end, forwarding preliminary values to on_preliminary and returning the final value.

Type Aliases

ApprovalFn

Decides per call whether approval is needed.

DescriptionFn

Produces a description per call.

InputAvailableHook

Called once the full input is available and valid.

InputDeltaHook

Called for each streamed input delta.

InputStartHook

Called when the model starts producing input for the tool.

ToModelOutputFn

Converts an execution output into what the model receives.

ToolOutputStream

Stream of outputs produced by one execution.

Derive Macros

JsonSchema

Derive macro for JsonSchema trait.