Unclear What makes Claude Code send this value, and how it changes matching of MCP allow rules, is not stated.
What
Auto mode lets Claude Code decide on its own whether to run a tool, using a classifier, a server-side check that judges each action. Allow rules are permissions you have set that pre-approve certain tools. MCP tools are tools supplied by outside servers you connect to Claude Code.
- Auto mode now drops bare MCP tool allow rules that would not be auto-approved anyway.
- It removes duplicate allow rules and caps how many are sent.
- When filtering succeeds, it sends a new optional true-or-false field,
mcp_allow_rules_exact, to the classifier. The field is sent only when true. - If filtering fails, the rules are sent unfiltered and without
mcp_allow_rules_exact, and a message says so. - Claude Code's internal report of incomplete auto mode context now also counts allow rules: the total, repeats, distinct rules and the cap.
Why
The classifier receives a shorter, cleaner list of rules. MCP allow rules may be matched differently as a result, so watch whether MCP tools you rely on are approved as before.
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What makes Claude Code send this value, and how it changes matching of MCP allow rules, is not stated.