{"version":"2.1.293","anchor":"mcp-tool-cache-bounded-by-key-count-and-weight-proto-st","canonical_anchor":"mcp-tool-cache-bounded-by-key-count-and-weight-proto-st","heading":"MCP tool cache gets size limits, plus other robustness fixes","tier":"notice","area":"MCP","scope":"individual","heads_up":false,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.293\/e\/mcp-tool-cache-bounded-by-key-count-and-weight-proto-st","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.293","markdown":"### MCP tool cache gets size limits, plus other robustness fixes\n\nClaude Code caps a cache of MCP tool entries by total size and per-tool count, strips __proto__ keys, and sometimes skips some environment lookups\n\n**Unclear.** It is not clear under what condition Claude Code skips the process and git lookups.\n\n**What**\n\nThis release brings three separate hardening changes:\n\n- MCP tool cache: MCP servers are outside services that give Claude extra tools. Claude Code now keeps a cache of MCP tool entries that drops the least recently used ones. It is capped by a total weight of 128000000 and by a count for each tool.\n\n- `__proto__` stripping: parsed data now has any `__proto__` keys removed. That name has a special meaning in JavaScript and can cause trouble if it is kept.\n\n- Environment details: when Claude Code gathers details about your environment, it skips the process measurements and the lookup of the current git commit under one particular condition.\n\n**Why**\n\nThese changes keep memory use bounded and make the handling of parsed data safer.\n\n- Area: MCP\n- Tier: You'll notice\n- Useful: 2\/5\n- Signal: 1\/5\n- Scope: individual\n- Heads-up: no"}