Built-in tools

An agent that can only talk isn’t much use. toolnexus ships opencode’s default toolset — 10 built-in tools — so a fresh toolkit can already act: run a command, read and edit files, search, fetch a URL, ask you a question. createToolkit() with no config at all still gives you a working, acting agent.

The ten tools

Tool	Does
bash	Run a shell command
read	Read a file
write	Write a file
edit	Edit a file in place
grep	Search file contents
glob	Find files by pattern
webfetch	Fetch a URL
question	Suspend and ask the user structured questions
apply_patch	Apply a patch to the tree
todowrite	Maintain a task list

Names and input schemas match opencode. They surface in the tool schema (toOpenAI/toAnthropic/toGemini) like MCP tools — not injected into the system prompt — so the model discovers them the same way it discovers every other source.

On by default — with two levels of off

Because bash/write/edit/apply_patch run commands and mutate the filesystem, you’ll want to lock them down on untrusted hosts. There’s a whole-source toggle and a per-tool map.

Turn the whole source off:

JavaScript

const tk = await createToolkit({ builtins: false })

Python

tk = await create_toolkit(builtins=False)

Go

tk, _ := toolnexus.CreateToolkit(ctx, toolnexus.Options{ Builtins: false })

Java

Toolkit tk = Toolkit.create(new Toolkit.Options().builtins(false));

C#

await using var tk = await Toolkit.CreateAsync(new Toolkit.Options { Builtins = false });

Or drop individual tools on the all-on baseline — here, disable bash while keeping the rest:

JavaScript

const tk = await createToolkit({ builtins: { tools: { bash: false } } })

Python

tk = await create_toolkit(builtins={"tools": {"bash": False}})

Go

tk, _ := toolnexus.CreateToolkit(ctx, toolnexus.Options{
    Builtins: toolnexus.BuiltinsConfig{Tools: map[string]bool{"bash": false}},
})

Java

Toolkit tk = Toolkit.create(new Toolkit.Options()
        .builtins(Map.of("tools", Map.of("bash", false))));

C#

await using var tk = await Toolkit.CreateAsync(new Toolkit.Options
{
    Builtins = new Dictionary<string, object?>
    {
        ["tools"] = new Dictionary<string, object?> { ["bash"] = false },
    },
});

Precedence

A whole-source false always wins. On the per-tool map, unknown names are ignored, and other tools stay on. If one of your own tools has the same name as a builtin, yours shadows it (the builtin is dropped) — so you can override a built-in tool by registering your own.

The same toggle can come from a top-level builtins block in the config the toolkit is built from, so a deployment can lock the toolset down without touching code.