Claude Code Security, Permissions, and Trust Boundaries

Model the trust boundary before changing defaults

Claude Code can read files, edit files, run commands, use git, access configured tools, and interact with external systems you connect. Security starts by deciding which of those capabilities are appropriate for the current task.

Default friction is not failure. Permission prompts, plan mode, local settings, and branch protection are all useful ways to slow down high-risk operations without blocking ordinary work.

Primary-source anchor: Anthropic documents that Claude Code can access the project, terminal, git state, CLAUDE.md, memory, and configured extensions when operating in a directory.

Choose permission mode by risk, not impatience

More automation is useful when the task is clear and the environment is safe. It is risky when the prompt is vague, the repo is unfamiliar, or the task touches secrets, production data, auth, billing, deployments, or infrastructure.

Plan-first workflows are cheap insurance for high-risk work. Ask Claude to inspect and propose changes without editing, then approve the plan once you understand the affected surface.

• Use manual review for unfamiliar repos and high-risk domains.
• Use allowlisted commands for trusted checks such as tests and builds.
• Use local settings for personal convenience, not shared policy.
• Use managed or project settings for team requirements.
• Use branch protection and CI as independent gates.

Do not turn prompts or logs into secret stores

Secrets should live in existing secret-management systems, not in prompts, transcripts, logs, screenshots, or CLAUDE.md. If Claude needs to use a credentialed tool, prefer scoped credentials through the tool or CI environment.

When debugging a secret-dependent failure, redact values before pasting output. Claude usually needs the error shape, environment name, and failing command, not the secret itself.

Review MCP servers and hooks as executable code

Hooks can execute commands. MCP servers can expose external tools and data. Both expand what Claude can do, so both belong in code review and security review when shared with a team.

The secure pattern is explicit: small hook scripts, named MCP tools, read-only defaults, scoped tokens, logging where needed, and separate approval for destructive operations.

• Hooks Risk comes from automatic execution at lifecycle points.
• MCP Risk comes from external data access and tool authority.
• CI Risk comes from running untrusted branch code with privileged tokens.

Preserve human accountability

Claude can draft, refactor, test, and summarize. It cannot own production accountability. For sensitive changes, require a human reviewer who understands the system and can reject plausible but unsafe diffs.

A good final handoff includes changed files, commands run, outputs, assumptions, known gaps, and whether any external systems were read or mutated.