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Tools

Tools extend an agent's capabilities. Rune supports several runtimes and a built-in tool library.

Tool Runtimes

Runtime Description
process Run a script (Python, Node, etc.) — stdin/stdout JSON protocol
wasm WebAssembly module via Wasmtime
container Docker container
agent Call another agent via A2A (agent_ref required)
builtin Rune's built-in rune@* tools

Process Tool Protocol

For runtime: process tools (e.g. .py, .js):

  1. Rune writes one JSON object to the tool's stdin
  2. The tool writes one JSON object to stdout and exits
  3. stderr is used for diagnostics
  4. Non-zero exit code is treated as failure

File extensions map to runtimes: .py → python3, .js/.mjs/.ts → node

Built-in Tools (rune@*)

All built-in tools use the rune@ prefix. The LLM sees rune__ (double underscore) in prompts.

Category Tools
Filesystem file-read, file-write, file-list, apply-patch
Web web-search, web-fetch
Shell shell-exec
System system-time, location-get
Memory memory-list, memory-store, memory-recall
Knowledge graph knowledge-add-entity, knowledge-add-relation, knowledge-query
Task queue task-post, task-claim, task-complete, task-list, event-publish
Scheduling schedule-create, schedule-list, schedule-delete, cron-create, cron-list, cron-cancel
Process process-start, process-poll, process-write, process-kill, process-list
Media image-analyze, image-generate, media-describe, media-transcribe, text-to-speech, speech-to-text
Agent agent-send, agent-list, agent-find, agent-spawn, agent-kill, a2a-discover, a2a-send
Docker docker-exec
Browser browser-navigate, browser-click, browser-type, browser-screenshot, browser-read-page, browser-close, browser-scroll, browser-wait, browser-run-js, browser-back
Channel channel-send
Canvas canvas-present

Tool Descriptor

Each custom tool has a YAML descriptor (e.g. tools/my_tool.yaml):

name: my_tool
version: 0.1.0
runtime: process
module: tools/my_tool.py
timeout_ms: 5000
capabilities: [filesystem]  # or [network], []
retry_policy:
  max_attempts: 2

See tools.yaml reference for full options.

Agent Tools

When runtime: agent, the tool calls another agent via A2A. Set agent_ref:

  • local://agent-name — agent in the same runtime
  • http://host:port/a2a/agent-name — remote A2A endpoint