The RE2 swap narrowed the contract: regex:true rejects lookaround ((?=…)/(?<=…))
and backreferences (\1). The internal JSDoc was updated, but the AGENT-VISIBLE
tool-spec (the only text the agent reads at call time, single-sourced to both
transports) still said 'a JS regular expression' — so an agent would write a
lookahead/backref and hit an error. Updated the .description and the regex flag
.describe() to name RE2 (linear-time, ReDoS-safe), list that char classes / word
boundaries / anchors / quantifiers work while lookaround and backreferences do
NOT, and keep the 'invalid/unsupported regex -> clear error' note.
mcp: tsc clean; tool-specs / server-instructions / contract tests green.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
claude code agent 227
086bc1bf8b