Claude with web search narrates before its JSON, so a strict JSON parser reports nothing

JSON.parse fails or returns an empty list

Verified 2026-09-24 · Confirmed by 0 builders · Trust 50/100

Cause

With web search on, the model writes prose before the JSON array. A parser that demands the whole reply be JSON discards a correct answer, which then reads like a clean result.

Fix

Find the first { or [ in the reply, walk forward counting bracket depth while skipping string contents and escaped characters, and parse the slice that closes at depth zero. Fail loudly if none is found.

Apply

function firstJson(t) { const s = t.search(/[[{]/); if (s < 0) throw new Error('no JSON'); let depth = 0, inStr = false, esc = false; for (let i = s; i < t.length; i++) { const c = t[i]; if (inStr) { if (esc) esc = false; else if (c === '\\') esc = true; else if (c === '"') inStr = false; continue; } if (c === '"') inStr = true; else if (c === '[' || c === '{') depth++; else if ((c === ']' || c === '}') && --depth === 0) return JSON.parse(t.slice(s, i + 1)); } throw new Error('unclosed JSON'); }

Affects: Claude with the web search tool, September 2026

Have your agent know this before it fails

claude mcp add --transport http footgun https://getfootgun.com/api/mcp