import * as fs from 'fs';
import * as path from 'path';
const LOG_FILE = '/tmp/mcp-tool-calls.log';
const MAX_LOG_SIZE = 5 * 1024 * 1024; // 5MB
interface LogEntry {
ts: string;
mcp: string;
tool: string;
conn: string | null;
project: string | null;
session: string | null;
args: Record<string, any>;
result?: string;
error?: string;
duration_ms?: number;
}
function rotateIfNeeded(): void {
try {
if (fs.existsSync(LOG_FILE)) {
const stats = fs.statSync(LOG_FILE);
if (stats.size > MAX_LOG_SIZE) {
const backup = LOG_FILE + '.1';
if (fs.existsSync(backup)) fs.unlinkSync(backup);
fs.renameSync(LOG_FILE, backup);
}
}
} catch (e) {
// Ignore rotation errors
}
}
function sanitizeArgs(args: Record<string, any>): Record<string, any> {
const sensitiveKeys = ['password', 'secret', 'token', 'key', 'credential', 'confirmation'];
const safe: Record<string, any> = {};
for (const [k, v] of Object.entries(args)) {
if (sensitiveKeys.some(s => k.toLowerCase().includes(s))) {
safe[k] = '[REDACTED]';
} else if (typeof v === 'string' && v.length > 100) {
safe[k] = v.substring(0, 100) + '...';
} else {
safe[k] = v;
}
}
return safe;
}
export function logToolCall(
mcpName: string,
toolName: string,
args: Record<string, any>,
connectionName?: string,
result?: string,
error?: string,
durationMs?: number
): void {
try {
rotateIfNeeded();
const project = path.basename(process.cwd());
const sessionId = process.env.CLAUDE_SESSION_ID || process.env.MCP_SESSION_ID || null;
const entry: LogEntry = {
ts: new Date().toISOString(),
mcp: mcpName,
tool: toolName,
conn: connectionName || null,
project,
session: sessionId,
args: sanitizeArgs(args),
};
if (result) entry.result = result.substring(0, 200);
if (error) entry.error = error.substring(0, 500);
if (durationMs !== undefined) entry.duration_ms = durationMs;
fs.appendFileSync(LOG_FILE, JSON.stringify(entry) + '\n');
} catch (e) {
// Don't let logging errors break the MCP
}
}
