Manage Feature Flags

Create, list, kill/restore, and delete Harness FME (Split.io-backed) Feature Flags via MCP.

Prerequisites

FME flags are workspace-scoped (not project-scoped). You must discover the workspace_id and environment_id before most operations.

Step 0a: List workspaces

Call MCP tool: harness_list
Parameters:
  resource_type: "fme_workspace"

Step 0b: List environments (per workspace)

Call MCP tool: harness_list
Parameters:
  resource_type: "fme_environment"
  workspace_id: "<workspace_id>"

Instructions

Step 1: List Existing Flags

Call MCP tool: harness_list
Parameters:
  resource_type: "fme_feature_flag"
  workspace_id: "<workspace_id>"

Filter by name, tags, or rollout status:

Call MCP tool: harness_list
Parameters:
  resource_type: "fme_feature_flag"
  workspace_id: "<workspace_id>"
  name: "dark_mode"
  tags: "ui"
  rollout_status_id: "<uuid>"   # discover via fme_rollout_status

Step 2: Get Flag Details

Call MCP tool: harness_get
Parameters:
  resource_type: "fme_feature_flag"
  workspace_id: "<workspace_id>"
  feature_flag_name: "<flag_name>"

For per-environment targeting/state, use fme_feature_flag_definition and pass environment_id.

Step 3: Create a Flag

Call MCP tool: harness_create
Parameters:
  resource_type: "fme_feature_flag"
  workspace_id: "<workspace_id>"
  traffic_type_id: "<traffic_type_id>"   # required by FME
  body:
    name: "dark_mode"
    description: "Enable dark mode UI theme"
    tags: ["ui", "rollout"]

Step 4: Kill or Restore a Flag (per environment)

Kill (turn the flag OFF in one environment):

Call MCP tool: harness_execute
Parameters:
  resource_type: "fme_feature_flag"
  action: "kill"
  workspace_id: "<workspace_id>"
  feature_flag_name: "<flag_name>"
  environment_id: "<environment_id>"

Restore (re-enable after a kill):

Call MCP tool: harness_execute
Parameters:
  resource_type: "fme_feature_flag"
  action: "restore"
  workspace_id: "<workspace_id>"
  feature_flag_name: "<flag_name>"
  environment_id: "<environment_id>"

Step 5: Archive / Unarchive a Flag

Call MCP tool: harness_execute
Parameters:
  resource_type: "fme_feature_flag"
  action: "archive"      # or "unarchive"
  workspace_id: "<workspace_id>"
  feature_flag_name: "<flag_name>"

Archiving is subject to OPA policy checks (returns 409 on violation). Unarchive returns 409 if dependent objects exist.

Step 6: Update Flag Metadata

Call MCP tool: harness_update
Parameters:
  resource_type: "fme_feature_flag"
  workspace_id: "<workspace_id>"
  feature_flag_name: "<flag_name>"
  body:
    description: "Updated description"
    tags: ["ui", "ga"]

Step 7: Delete a Flag

Call MCP tool: harness_delete
Parameters:
  resource_type: "fme_feature_flag"
  workspace_id: "<workspace_id>"
  feature_flag_name: "<flag_name>"

FME Resource Types Reference

Examples

• "Create a feature flag for dark mode" — Create fme_feature_flag with body: { name: "dark_mode", ... }
• "Kill the experimental-search flag in production" — Execute kill with production environment_id
• "Restore the new-checkout flag in staging" — Execute restore with staging environment_id
• "List all feature flags in my workspace" — List fme_feature_flag for workspace
• "Archive the stale beta_banner flag" — Execute archive

Performance Notes

• Always discover workspace_id and environment_id before kill/restore — wrong environment can affect production.
• List existing flags before creating to avoid duplicates.
• FME does not expose a single "toggle" action — use kill (off) and restore (on) per environment.

Troubleshooting

Flag won't kill/restore

• environment_id is required — kills are per-environment
• Confirm feature_flag_name is exact (case-sensitive)
• Verify the flag lives in the specified workspace_id

Flag Not Found

• FME flags are workspace-scoped — confirm the correct workspace_id
• Use harness_list with resource_type: "fme_feature_flag" and no filters to see all flags in the workspace

Archive fails with 409

• An OPA policy may block archival — review governance policies
• For unarchive, remove dependent segments/targeting before retrying