import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
import { z } from 'zod';
import { execFile } from 'node:child_process';
import { access } from 'node:fs/promises';
import { constants } from 'node:fs';
import { join } from 'node:path';
const MAKE_TIMEOUT = 120_000;
const MAX_BUFFER = 1024 * 1024;
export function registerMakeTool(server: McpServer): void {
server.registerTool(
'gerbil_make',
{
title: 'Run Makefile Target',
description:
'Run a Makefile target in a Gerbil project directory. ' +
'Returns structured output with exit code, stdout, and stderr. ' +
'Defaults to the default target if none specified.',
inputSchema: {
project_path: z
.string()
.describe('Directory containing the Makefile'),
target: z
.string()
.optional()
.describe(
'Make target to run (e.g. "build", "clean", "install"). Defaults to the default target.',
),
timeout: z
.number()
.optional()
.describe('Timeout in milliseconds (default: 120000)'),
},
},
async ({ project_path, target, timeout }) => {
// Check that the Makefile exists
const makefilePath = join(project_path, 'Makefile');
try {
await access(makefilePath, constants.R_OK);
} catch {
return {
content: [
{
type: 'text' as const,
text: `No Makefile found in ${project_path}`,
},
],
isError: true,
};
}
const args = target ? [target] : [];
const makeTimeout = timeout ?? MAKE_TIMEOUT;
const result = await runMake(args, project_path, makeTimeout);
if (result.timedOut) {
return {
content: [
{
type: 'text' as const,
text: `make timed out after ${Math.round(makeTimeout / 1000)} seconds.`,
},
],
isError: true,
};
}
if (result.exitCode === 127) {
return {
content: [
{
type: 'text' as const,
text: 'make not found. Ensure GNU Make is installed and in PATH.',
},
],
isError: true,
};
}
const output = [result.stdout, result.stderr]
.filter(Boolean)
.join('\n')
.trim();
const targetStr = target ?? '(default)';
if (result.exitCode === 0) {
const sections = [`make ${targetStr} succeeded.`];
if (output) {
sections.push('', output);
}
return {
content: [{ type: 'text' as const, text: sections.join('\n') }],
};
}
return {
content: [
{
type: 'text' as const,
text: `make ${targetStr} failed (exit code ${result.exitCode}):\n\n${output}`,
},
],
isError: true,
};
},
);
}
function runMake(
args: string[],
cwd: string,
timeout: number,
): Promise<{ stdout: string; stderr: string; exitCode: number; timedOut: boolean }> {
return new Promise((resolve) => {
execFile(
'make',
args,
{ timeout, maxBuffer: MAX_BUFFER, cwd },
(error, stdout, stderr) => {
if (error) {
const timedOut = error.killed === true;
const code = (error as NodeJS.ErrnoException).code;
const exitCode =
typeof error.code === 'number'
? error.code
: code === 'ENOENT'
? 127
: 2;
resolve({
stdout: stdout ?? '',
stderr: stderr ?? '',
exitCode,
timedOut,
});
} else {
resolve({
stdout: stdout ?? '',
stderr: stderr ?? '',
exitCode: 0,
timedOut: false,
});
}
},
);
});
}
