Agent skills

Mostly Good Metrics publishes one portable skill set for Codex, Claude Code, and other agents supported by the standard skills installer. Skills describe how to instrument an app, analyze metrics, diagnose funnels, build dashboards, measure retention, audit instrumentation, and run experiments.

The canonical source is Mostly-Good-Metrics/skills.

Install for Codex

npx skills add Mostly-Good-Metrics/skills --agent codex --global --yes

Install for Claude Code

The Claude Code plugin is the simplest path: it installs the MGM MCP connection and mirrors the complete skill set.

/plugin marketplace add Mostly-Good-Metrics/claude-plugin
/plugin install mostly-good-metrics@mostly-good-metrics

To install only the portable skills instead:

npx skills add Mostly-Good-Metrics/skills --agent claude-code --global --yes

Connect MGM data

Skills are instructions; the MGM MCP server provides the tools and data. Connect this streamable HTTP endpoint:

https://app.mostlygoodmetrics.com/mcp

Authentication is browser-based OAuth. The first MGM tool call asks you to sign in and approve access; you do not copy an API key into the agent.

The skills can also use the mgm CLI for local scripting or when MCP is not connected.

Verify discovery

1. Restart the agent client if it was open during installation.
2. Ask it to list its MGM skills or explicitly invoke instrument-my-app.
3. Ask it to call mgm_whoami or list MGM projects; complete OAuth if prompted.
4. Confirm the agent names the project it selected before it reads or changes saved analytics.

Included skills

Skill	Use it for
instrument-my-app	Install an SDK and add safe event tracking
audit-instrumentation	Diagnose missing, duplicated, or misleading data
analyze-metrics	Answer product questions with real MGM data
build-dashboard	Create reusable queries and decision-focused widgets
funnel-doctor	Find and segment conversion drop-offs
retention-cohorts	Compare mature retention cohorts
run-experiment	Plan and operate an MGM experiment
weekly-review	Produce a compact week-over-week report

Repository-level instructions still apply. An MGM skill explains the product workflow; the target repository's AGENTS.md or CLAUDE.md explains its build, test, review, and safety conventions.

Customer MCP versus Support MCP

These public skills use the tenant-scoped customer MCP. MGM's admin-only Support MCP is a separate, private, read-only debugging surface and is intentionally not installed or documented as a customer skill.