mcp-harness-fme — Erwann Mest

Features

28 tools — covers workspaces, environments, feature flags, flag definitions, segments, rule-based segments, and change requests.
Kill & restore — instantly kill a flag to force all traffic to the default treatment, or restore it with a single tool call.
Safety guard — every destructive operation (delete, kill, archive, disable) requires confirm: true, preventing accidental changes.
Rule-based segments — create, update, enable, disable, and submit change requests for rule-based segments per environment.
Change request flow — submit segment definition changes with optional approvers for teams that require approval gates.
Zero-config startup — reads MCP_HARNESS_FME_API_KEY from the environment and exits immediately if it is missing.

Install

Add to your MCP client config (see Usage below), or install globally to run manually:

npx --yes @kud/mcp-harness-fme@latest

Set the environment variable MCP_HARNESS_FME_API_KEY to your Harness FME API key before starting the server.

Usage

Claude Desktop / Claude Code

{
  "mcpServers": {
    "harness-fme": {
      "command": "npx",
      "args": ["--yes", "@kud/mcp-harness-fme@latest"],
      "env": {
        "MCP_HARNESS_FME_API_KEY": "your_api_key"
      }
    }
  }
}

For Claude Code, add via the CLI:

claude mcp add --transport stdio --scope user harness-fme \
  --env MCP_HARNESS_FME_API_KEY=your_api_key \
  -- npx --yes @kud/mcp-harness-fme@latest

Available tools

Tool	Description
`list_workspaces`	List all FME workspaces in the account
`list_environments`	List all environments in a workspace
`list_traffic_types`	List all traffic types in a workspace
`list_rollout_statuses`	List rollout status definitions for a workspace
`list_feature_flags`	List feature flags in a workspace (filter by tag, status, name)
`get_feature_flag`	Get metadata for a specific feature flag
`create_feature_flag`	Create a new feature flag for a given traffic type
`update_feature_flag`	Update a flag's description, tags, owners, or rollout status
`delete_feature_flag`	Permanently delete a feature flag (`confirm: true` required)
`archive_feature_flag`	Archive a flag, removing it from active use (`confirm: true` required)
`unarchive_feature_flag`	Restore a previously archived feature flag
`kill_feature_flag`	Kill a flag in an environment — forces default treatment (`confirm: true` required)
`restore_feature_flag`	Restore a killed feature flag in an environment
`list_flag_definitions`	List flag targeting rules in an environment
`get_flag_definition`	Get treatments and targeting rules for a flag in an environment
`create_flag_definition`	Activate a flag in an environment with treatments and targeting rules
`update_flag_definition`	Fully replace a flag's targeting rules in an environment
`delete_flag_definition`	Remove a flag's targeting rules from an environment (`confirm: true` required)
`list_segments`	List all segments in a workspace
`list_rule_based_segments`	List all rule-based segments in a workspace
`get_rule_based_segment`	Get a rule-based segment's workspace-level metadata
`create_rule_based_segment`	Create a new rule-based segment in a workspace
`delete_rule_based_segment`	Permanently delete a rule-based segment (`confirm: true` required)
`list_rule_based_segment_definitions`	List rule-based segment definitions in an environment
`update_rule_based_segment_definition`	Update a rule-based segment's rules in an environment
`enable_rule_based_segment_definition`	Activate a rule-based segment in an environment
`disable_rule_based_segment_definition`	Remove a rule-based segment from an environment (`confirm: true` required)
`create_rule_based_segment_change_request`	Submit a change request for a segment definition with optional approval flow

Development

git clone https://github.com/kud/mcp-harness-fme.git
cd mcp-harness-fme
npm install
npm run dev           # run from source with tsx
npm run inspect:dev   # MCP Inspector at http://localhost:5173
npm test              # vitest
npm run build         # compile to dist/

The server reads MCP_HARNESS_FME_API_KEY at startup and exits immediately if it is absent. All tools are defined in src/index.ts.