# update_custom_hook [MAINTENANCE] b4f4627f — the previously-missing generic enable/disable/edit path for a user-defined hook (id returned by add_custom_hook / get_custom_hooks): patches name, event, matcher, script_sh, script_ps1, blocking, and/or enabled without the delete+recreate round-trip add_custom_hook/delete_custom_hook would otherwise require. At least one editable field is required. Renaming re-derives the slug (same reserved-name / uniqueness checks as add_custom_hook); the db layer raises ValueError for a bad event, the reserved 'sprint_guard' name, or a slug collision — surfaced as {error}. Returns {error} (never raises) when hook_id doesn't resolve for this project. Flipping enabled true -> false also removes any already-written .claude/hooks/.* files immediately (best-effort, when the project has a resolvable repo_path) instead of waiting for the next generate_handoff to simply stop re-writing them — reported back as removed_files when any were deleted. Persistent-state disclosure: on hosted Meridian, supplied text and project/session metadata are sent to and stored in Meridian's service; self-hosted deployments keep them in the configured local SQLite/Postgres database. This data is visible in the dashboard/API and later project context or handoffs. Delete individual tasks, notes, or decisions where supported, or delete the project/account using the documented controls. Do not include secrets. Agent View of the PolicyLayer registry record for `update_custom_hook`. HTML page: https://policylayer.com/tools/io-github-ajc3xc-meridian/update-custom-hook ## Facts - Tool: `update_custom_hook` - Server: Meridian (`@meridianmcp/mcp`) — https://policylayer.com/tools/io-github-ajc3xc-meridian.md - Install: `npx -y @meridianmcp/mcp` - Homepage: https://github.com/meridianmcp/Meridian - Risk category: Write (Medium risk) - Registry record: grade F, identity unverified - Server auth posture: open - Server CORS policy: * - Server rate-limited: no - Parameters: 10 (1 required) - Recommended policy verdict: Rate-limited ## Parameters | Parameter | Type | Required | Description | | --- | --- | --- | --- | | `name` | string | no | New human-readable name; re-derives the slug (must not be 'sprint_guard' or collide with another hook's slug on this project). | | `event` | string | no | New hook event. | | `enabled` | boolean | no | Enable/disable this hook. Disabling immediately removes any already-written artifact files for it (best-effort). | | `hook_id` | string | yes | The hook id to update. | | `matcher` | string | no | New Claude Code tool-name matcher regex; ignored for Stop hooks. | | `blocking` | boolean | no | true = real exit-code-blocking semantics. false = advisory/non-blocking. | | `script_sh` | string | no | New POSIX shell script body. | | `project_id` | string | no | | | `script_ps1` | string | no | New PowerShell script body. | | `project_name` | string | no | Project name — an alternative to project_id; resolved to the id internally. project_id wins if both are given. | Parameters from the server's own tool schema. ## Example call (MCP tools/call, JSON-RPC 2.0) ```json { "jsonrpc": "2.0", "id": 1, "method": "tools/call", "params": { "name": "update_custom_hook", "arguments": { "hook_id": "" } } } ``` ## Why update_custom_hook is rated Medium An AI agent can call update_custom_hook faster than any human can review: one bad instruction and it creates or modifies resources in Meridian by the hundred, each call as confident as the last. Risk signals: High parameter count (10 properties) ## Use case AI agents use update_custom_hook to create or update resources in Meridian, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Meridian environment. ## Recommended policy (PolicyLayer) Verdict: **Rate-limited**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches Meridian: ```json { "version": "1", "default": "deny", "tools": { "update_custom_hook": { "limits": [ { "counter": "update_custom_hook_rate", "window": "minute", "max": 30, "scope": "grant" } ] } } } ``` ## Other tools on Meridian (174) - `archive_decision` — Destructive — https://policylayer.com/tools/io-github-ajc3xc-meridian/archive-decision.md - `batch_mutate` — Destructive — https://policylayer.com/tools/io-github-ajc3xc-meridian/batch-mutate.md - `claim_sprint_item` — Destructive — https://policylayer.com/tools/io-github-ajc3xc-meridian/claim-sprint-item.md - `clear_capability_profile` — Destructive — https://policylayer.com/tools/io-github-ajc3xc-meridian/clear-capability-profile.md - `clone_profile_layer` — Destructive — https://policylayer.com/tools/io-github-ajc3xc-meridian/clone-profile-layer.md - `delete_custom_hook` — Destructive — https://policylayer.com/tools/io-github-ajc3xc-meridian/delete-custom-hook.md - `delete_note` — Destructive — https://policylayer.com/tools/io-github-ajc3xc-meridian/delete-note.md - `delete_sprint_item_pointer` — Destructive — https://policylayer.com/tools/io-github-ajc3xc-meridian/delete-sprint-item-pointer.md - `fan_out_sprint_items` — Destructive — https://policylayer.com/tools/io-github-ajc3xc-meridian/fan-out-sprint-items.md - `purge_ai_log` — Destructive — https://policylayer.com/tools/io-github-ajc3xc-meridian/purge-ai-log.md - `record_handoff_correction` — Destructive — https://policylayer.com/tools/io-github-ajc3xc-meridian/record-handoff-correction.md - `release_docx_region_claims` — Destructive — https://policylayer.com/tools/io-github-ajc3xc-meridian/release-docx-region-claims.md - `request_hitl` — Destructive — https://policylayer.com/tools/io-github-ajc3xc-meridian/request-hitl.md - `reset_plugin_override` — Destructive — https://policylayer.com/tools/io-github-ajc3xc-meridian/reset-plugin-override.md - `reset_profile_layer` — Destructive — https://policylayer.com/tools/io-github-ajc3xc-meridian/reset-profile-layer.md - `complete_wave_gate` — Execute — https://policylayer.com/tools/io-github-ajc3xc-meridian/complete-wave-gate.md - `execute_batch` — Execute — https://policylayer.com/tools/io-github-ajc3xc-meridian/execute-batch.md - `prospect_symbol` — Execute — https://policylayer.com/tools/io-github-ajc3xc-meridian/prospect-symbol.md - `run_verification` — Execute — https://policylayer.com/tools/io-github-ajc3xc-meridian/run-verification.md - `start_session` — Execute — https://policylayer.com/tools/io-github-ajc3xc-meridian/start-session.md - `analyze_model_efficiency` — Read — https://policylayer.com/tools/io-github-ajc3xc-meridian/analyze-model-efficiency.md - `analyze_sprint` — Read — https://policylayer.com/tools/io-github-ajc3xc-meridian/analyze-sprint.md - `batch_read` — Read — https://policylayer.com/tools/io-github-ajc3xc-meridian/batch-read.md - `find_outputs_by_source` — Read — https://policylayer.com/tools/io-github-ajc3xc-meridian/find-outputs-by-source.md - `find_similar_equation` — Read — https://policylayer.com/tools/io-github-ajc3xc-meridian/find-similar-equation.md - `find_similar_figure` — Read — https://policylayer.com/tools/io-github-ajc3xc-meridian/find-similar-figure.md - `find_similar_table` — Read — https://policylayer.com/tools/io-github-ajc3xc-meridian/find-similar-table.md - `find_symbol_usages` — Read — https://policylayer.com/tools/io-github-ajc3xc-meridian/find-symbol-usages.md - `get_agent_instructions` — Read — https://policylayer.com/tools/io-github-ajc3xc-meridian/get-agent-instructions.md - `get_blog_posts` — Read — https://policylayer.com/tools/io-github-ajc3xc-meridian/get-blog-posts.md - …and 144 more: https://policylayer.com/tools/io-github-ajc3xc-meridian.md ## For agents This record is a snapshot. Live verdicts and the full registry: - Check every server in your MCP config at once: `npx -y policylayer stack` - Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md) - Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events` --- Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=io-github-ajc3xc-meridian · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/io-github-ajc3xc-meridian