Claude Code 2.1.295 adds control when policy hooks fail
Anthropic released Claude Code 2.1.295 on October 8 with an option to block an action when its command or HTTP hook fails. It also expands the descriptions loaded through MCP tool search and changes how many skills subagents preload.
The practical issue is what happens when a team’s own check breaks. A missing script or unavailable service can interrupt the check itself. This release gives developers a more explicit choice about that failure path.
Failure handling still needs a setting
The hooks reference keeps continue as the default. Developers must set onFailure to block on an eligible command or HTTP hook. Failures include a process that cannot start, a timeout, an unexpected exit code, an HTTP connection or status error, and invalid structured output. A command’s ordinary text output does not itself count as failure.
The event matters. A failing PreToolUse hook blocks the proposed tool call. A failing UserPromptSubmit hook blocks the prompt, while PermissionRequest denies the request. The setting has no effect on Stop, SubagentStop, TaskCompleted or TeammateIdle hooks, or on command hooks running with async or asyncRewake.
A useful first check is a deliberately missing handler in a disposable project. Confirm that the action is blocked, then restore the handler and test a normal approval and a deliberate rejection. Anthropic documents this failure test. ByteForward has not independently executed it.
A hook sits inside a larger permission system
Anthropic’s permissions documentation distinguishes a hook decision from the final result. PreToolUse decisions respect deny and ask rules. However, an installed mod handling tool.check answers later and can approve a call blocked by a hook unless that hook comes from managed settings. That exception makes the location of an organization’s policy important.
Teams should inspect both the hook configuration and the extensions that participate in approval. A successful demonstration on one laptop does not establish the behavior of a differently managed installation. Treat the new setting as one control in that configuration, and verify the final action as well as the message shown in the transcript.
The Bash sandbox guide describes a separate operating system boundary for shell commands and their child processes. File tools, MCP servers and hooks run outside that shell sandbox. It supports macOS, Linux and WSL2, while native Windows commands run without it. A blocking hook therefore does not establish that every extension or external tool is isolated.
Longer tool descriptions have a narrow scope
The versioned release raises the cutoff for MCP tool descriptions loaded through tool search from 2,048 to 16,384 characters. It does not announce a larger model context window or an equivalent increase for every server instruction.
The MCP guide explains why this distinction matters. Tool search defers full definitions until Claude needs them, loading tool names and server instructions at the start. Authors still need clear instructions that help the agent decide when to discover a tool. The guide currently describes a 2,048 character default for descriptions and server instructions, which differs from the newer release note for searched tool descriptions.
For version 2.1.295, use the narrower release note when assessing that specific change. Keep essential guidance near the start and check the content actually loaded in the installed client. More available description space does not demonstrate better tool selection or lower costs. Those outcomes depend on the tools, task and model, and this release provides no comparative measurements.
Skill preloading is different from skill access
The updated subagent guide says startup preloading takes the first 32 distinct names from the skills field and inserts their full content. Additional project, user and plugin skills can still be discovered and invoked through the Skill tool. Removing a skill from the preload list therefore does not revoke access to it.
This gives teams a reason to review what every worker needs immediately. Put essential task guidance in the startup selection, then check that later skill discovery works when it is needed. If the goal is restricting capability, inspect tool permissions rather than relying on the preload count.
Test the failure paths before a wider rollout
Start with a representative task in a disposable environment. Include a broken check, a check that denies an action, an external tool with a long description and a worker that needs a skill outside its initial selection. Record what actually happens at the destination. Then compare the configuration with the one that will run unattended work.
The useful result is a repeatable account of which actions proceed, which stop and what an operator must repair. That is a stronger basis for adoption than assuming a version upgrade automatically enforces the policy the team intended.
For earlier context, see ByteForward’s October 2 coverage of Claude Code recovery and tool controls.
Illustrative programming photograph by Negative Space, available under CC0. The original photograph is unchanged and does not depict Claude Code.
