autobot-wasm

WebAssembly plugin for Autobot. Write tools in any language (Rust, Go, C, AssemblyScript, etc.), compile to .wasm, and expose them to the LLM agent.

Prerequisites

• Wasmer runtime v2.x installed
• WASMER_DIR environment variable set

Installation

Add to your shard.yml:

dependencies:
  autobot-wasm:
    github: crystal-autobot/autobot-wasm
    version: ~> 0.1.0

Then require it alongside autobot:

require "autobot"
require "autobot-wasm"

The plugin registers itself automatically.

How it works

1. Place .wasm + .json manifest pairs in workspace/wasm/
2. On startup, the plugin discovers all manifests, compiles the WASM modules, and registers them as tools
3. Tools are exposed to the LLM with the wasm_ prefix (e.g., wasm_string_reverse)
4. When called, parameters are passed as JSON in argv[1] via WASI, and the tool writes its result to stdout

Manifest format

Each tool needs a JSON manifest alongside its .wasm file:

workspace/wasm/
  string_reverse.json
  string_reverse.wasm

Example string_reverse.json:

{
  "name": "string_reverse",
  "description": "Reverse a string and return the result",
  "parameters": {
    "properties": {
      "input": { "type": "string", "description": "The string to reverse" }
    },
    "required": ["input"]
  },
  "timeout": 30,
  "env": {}
}

Fields

Parameter properties

Each property in parameters.properties supports:

• type — string, integer, number, boolean, array, object
• description — Human-readable description
• enum — Array of allowed values (strings only)
• minimum / maximum — Numeric bounds
• items — Schema for array items

Writing a WASM tool

Communication protocol

• Arguments are received via WASI args: argv[0] is the tool name, argv[1] is a JSON string of parameters
• Output is written to stdout
• The tool should exit with code 0 on success

Example in Rust

use std::env;
use std::io;

fn main() {
    let args: Vec<String> = env::args().collect();
    let params: serde_json::Value = serde_json::from_str(&args[1]).unwrap();

    let input = params["input"].as_str().unwrap();
    let reversed: String = input.chars().rev().collect();

    print!("{}", reversed);
}

Compile with:

cargo build --target wasm32-wasi --release
cp target/wasm32-wasi/release/string_reverse.wasm workspace/wasm/

Example in C

#include <stdio.h>
#include <string.h>

int main(int argc, char *argv[]) {
    // argv[1] contains JSON params - parse as needed
    // Write result to stdout
    printf("Hello from C WASM tool!");
    return 0;
}

Compile with:

clang --target=wasm32-wasi -o workspace/wasm/hello.wasm hello.c

Limits

• Output: Truncated at 50 KB
• Timeout: Configurable per tool (default 30s)
• Memory: Managed by the Wasmer runtime

Development

shards install
crystal spec
crystal tool format
./bin/ameba

License

MIT