Unclear It is not clear which MCP tools carry a standard key or what condition decides whether they are kept.
What
MCP tools come from outside servers you connect to Claude Code. When Claude Code builds the list of tools Claude may use, it now also leaves out any MCP tool that carries a standard key, an extra label some MCP tools have, whenever a new condition based on the tool list is not met.
The existing filtering by --tools is unchanged. A tool left out that way still produces the warning that it "is not on this session's --tools list and no deny rule names it; withheld. Name it in --tools to offer it".
Why
Some MCP tools may no longer appear in a session even though nothing you configured removes them.
Names in the bundle--tools
--tools
Claude Code changelog modified, high confidence
* Fixed split-pane agent teammates not inheriting the tool deny and `--tools` rules given on the leader's command linesee the edit
--tools
Orchestrate teams of Claude Code sessions modified, high confidence
An [in-process](#choose-a-display-mode) teammate runs under the lead's live allow and deny rules, so [`--disallowedTools`](/docs/en/cli-reference#cli-flags), `--tools`, and `--allowedTools` all apply to it. For a split-pane teammate, check…see the edit
--tools
Tools reference modified, high confidence
A subagent has the task-tracking tools only when your session has them, whatever model the subagent runs. An in-process [agent team](/docs/en/agent-teams.md) teammate has the task-tracking tools when your session does. A [split-pane](/docs…see the edit
--tools
Orchestrate teams of Claude Code sessions modified, high confidence
An [in-process](#choose-a-display-mode) teammate runs under the lead's live allow and deny rules, so [`--disallowedTools`](https://code.claude.com/docs/en/cli-reference#cli-flags), `--tools`, and `--allowedTools` all apply to it. For a spl…see the edit
--tools
Connect Claude Code to tools via MCP modified, high confidence
If you deny `ToolSearch` or leave it out of [`--tools`](https://code.claude.com/docs/en/cli-reference#cli-flags), MCP tools load upfront instead, but a request can still carry a placeholder `defer_loading` entry. If a gateway rejects that …see the edit
--tools
Tools reference modified, high confidence
The tool never prompts for permission, and [PreToolUse hooks](https://code.claude.com/docs/en/hooks.md#pretooluse) don't run for it. While any other tool remains, you can't block it either: [deny and ask rules](https://code.claude.com/docs…see the edit
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubt
It is not clear which MCP tools carry a standard key or what condition decides whether they are kept.
Anthropic's documentation agrees
--tools on Claude Code changelog