exploring-mcp-tool-usage

The front door for someone who wants to look at how their tool server is doing but has not picked a question yet — it lays out the questions worth asking and sends you to whatever answers each one.

WHEN TO USE

SCOPE

USE FOR

Get the headline numbers for one tool: calls, errors, speed, and reach.
See which app is calling your tools most, and how reliably it goes.
Find out what gets called right before or right after one tool.
Check what description a tool is actually registered with.

This is a saved copy of the skill's SKILL.md instructions. It may differ from the upstream file or the version you install.

In this document (7)

Exploring MCP tool usage

Any MCP server instrumented with the @posthog/mcp SDK emits a $mcp_tool_call event every time an agent invokes a tool. This skill is the front door for a user who knows they want to look at their MCP tool usage but hasn't picked a specific question. Offer the menu below, then route to the tool — or the focused skill — that answers what they choose.

Governed metric first

When the question asks for an MCP failure rate or percentage, call posthog:metric-list before any typed tool or SQL recipe and look for mcp_tool_call_fail_pct. Run an approved, non-drifted match with posthog:data-catalog-metric-run for the canonical headline. If the user also asks which tool or harness drives failures, answer the headline first, then use the per-tool workflows below for a noncanonical breakdown. If no governed metric matches, say so and label the derived rate noncanonical.

Every per-tool tool here is gated behind the mcp-analytics flag, takes a toolName (the effective tool name — resolved server-side, so pass the name the agent actually invokes — except posthog:query-mcp-tool-failures, which matches $exception events and so takes the raw registered $mcp_tool_name) plus a dateRange, and runs the same query runner the tool-detail UI uses. So results match the UI, and you never hand-write the HogQL.

Ask the user…	Answered by
"Which tools fail most, or are slowest?"	`exploring-mcp-tool-quality` (ranks all tools), then `posthog:query-mcp-tool-stats` to drill in
"How is tool X doing overall?"	`posthog:query-mcp-tool-stats` — calls, errors, p50/p95, users, sessions, intents
"How has tool X trended?"	`posthog:query-mcp-tool-daily-stats` — day-by-day series
"Why is tool X failing?"	`posthog:query-mcp-tool-failures` — top error messages, by harness (raw tool name)
"Who uses tool X the most?"	`posthog:query-mcp-tool-top-users` — top callers (incl. person email/name)
"What gets called right before/after tool X?"	`posthog:query-mcp-tool-neighbors` (`neighborDirection: before`/`after`)
"What are agents trying to do with tool X?"	`posthog:query-mcp-tool-sample-intents` — recent agent intents
"What description is tool X registered with?"	`posthog:query-mcp-tool-descriptions` — distinct descriptions seen
"Which harnesses use my MCP, how reliably?"	`posthog:query-mcp-harness-breakdown` — calls/errors/sessions per client
"What are agents trying to do, across all tools?"	`exploring-mcp-intent-clusters` — semantic goal clusters
"Who is connecting, and how active are they?"	`posthog:mcp-analytics-sessions-list` — one row per session, with client and person
"What did this one session do?"	`exploring-mcp-sessions` — a single agent run's tool sequence

Finding the tool name

The per-tool tools need a toolName. If the user named a tool, pass it. If they asked a broad "which tool…" question, start with exploring-mcp-tool-quality to rank the tools, pick the one that stands out, then drill in with the per-tool tools above. The name to pass is the effective tool name (the inner tool for single-exec wrapper calls) — the same string the tool-quality ranking returns. The one exception is posthog:query-mcp-tool-failures, which matches $exception events by the raw registered $mcp_tool_name, not the effective inner tool.

How to use a per-tool tool

Call it with the tool name and a window, e.g. for the headline numbers of a tool:

posthog:query-mcp-tool-stats  { "toolName": "<tool>", "dateRange": { "date_from": "-7d" } }

Then offer a natural follow-up from the menu — e.g. after posthog:query-mcp-tool-stats shows a high error rate, reach for posthog:query-mcp-tool-failures; after it shows broad reach, reach for posthog:query-mcp-tool-top-users or posthog:query-mcp-tool-neighbors.

When to drop to SQL

Covered by a typed tool — don't hand-write SQL for these:

Question	Tool
One tool's headline numbers	`posthog:query-mcp-tool-stats`
One tool's day-by-day trend	`posthog:query-mcp-tool-daily-stats`
One tool's top errors	`posthog:query-mcp-tool-failures`
One tool's top callers	`posthog:query-mcp-tool-top-users`
Tools called before/after one tool	`posthog:query-mcp-tool-neighbors`
One tool's recent agent intents	`posthog:query-mcp-tool-sample-intents`
One tool's registered descriptions	`posthog:query-mcp-tool-descriptions`
Usage split by client harness	`posthog:query-mcp-harness-breakdown`
List sessions	`posthog:mcp-analytics-sessions-list`
One session's tool calls	`posthog:mcp-analytics-sessions-tool-calls`

Not covered — use posthog:execute-sql:

Cross-tool rankings (the tool-quality matrix — "which tool errors most?")
Errored-session filtering (the session list has no error filter or error count)
Effective tool names inside a session (posthog:mcp-analytics-sessions-tool-calls returns the raw $mcp_tool_name, not the inner tool of a wrapper call)
Any custom breakdown

posthog:execute-sql is also the fallback when the mcp-analytics flag is off — every tool in the table above is gated behind it, execute-sql is not. Query $mcp_tool_call directly; the schema and recipes are in models-mcp.md.

Related skills

exploring-mcp-tool-quality — rank tools by error rate / latency / reach, then drill in
exploring-mcp-sessions — a single agent run and its tool sequence
exploring-mcp-intent-clusters — agent goals grouped by semantic similarity

This skill ships inside the PostHog AI Plugin. Listed package contents include 3 slash commands, 1 agent, hooks and an MCP server. Installed components and skill versions may vary by AI tool.

Install just this skill

Run this outside your AI tool, using Node.js 22.20.0 or newer. Skills CLI 1.7.2 skips skill selection; prompts cancel installation without an interactive terminal. If choosing Project when asked about installation scope, open your project's folder before running this.

Install checklist

Check selected tools if a picker appears; Claude Code may be unchecked under Additional agents. ↑/↓ moves, Space toggles selections, Enter confirms.
Without a tool picker, check Installing to: for your intended tool. Stop if it names a different tool.
If asked, choose Symlink (Recommended) for shared files or Copy to all agents for separate copies; review the summary before confirming installation.
Install the find-skills skill? defaults to Yes, adding another skill for all projects. Choose No if you don't want that extra installation.

Skills CLI 1.7.2 sends install data to skills.sh by default, including the source, skill names, target tools and file details; GitHub sources are reported only when GitHub confirms the repository is public, while other remote sources can also be reported. Confirmed-public GitHub sources also trigger a security-audit request. Before installing, set the environment variable DO_NOT_TRACK=1 or DISABLE_TELEMETRY=1 to disable both.

npx skills add posthog/ai-plugin --skill "exploring-mcp-tool-usage" --full-depth

After installing for Claude Code, open it in the installation project if you chose Project; Global makes the skill available across projects on this computer. Once Claude Code loads the skill, its description helps Claude decide when to use it.

If installation created a top-level skills folder that did not exist when your Claude Code session started, run /reload-skills in that session. Run it again after later changes in that folder.

MCP server required

The skill's steps call for tools from the PostHog MCP server. Installing just this skill doesn't add that connection; set it up in your AI tool if it isn't there yet: PostHog MCP setup. Installing the whole plugin instead includes the connection settings.

Requirements for the PostHog MCP server

Connecting is free; sign in with your PostHog account.
Some tools use AI internally and may incur PostHog AI charges. Those tools require AI data processing to be enabled in your organization settings.

Install the whole plugin

This route installs the posthog plugin package selected for your AI tool.

Claude Code

Add PostHog's marketplace, then install the plugin

Run both lines in a terminal. They install PostHog's posthog plugin: this skill, PostHog's other skills, and a connection to PostHog's hosted MCP server.

claude plugin marketplace add PostHog/ai-plugin

02
```
claude plugin install posthog@posthog
```

Installation and loading

The plugin installs for you in every project and loads the next time you start Claude Code, or after /reload-plugins in an open session.
To connect your PostHog account, start claude, type /mcp, select plugin:posthog:posthog and follow the browser prompts.

Good to know

The plugin includes PostHog's session-capture hook; PostHog's README says it sends sessions to LLM Analytics only when POSTHOG_LLMA_CC_ENABLED=true and POSTHOG_API_KEY are both set.
If you use the separate posthog-telemetry plugin, PostHog says to keep only one of the two, because both register the same hook.
On a self-hosted PostHog, this route's MCP connection won't reach your instance: the plugin's config is fixed to https://mcp.posthog.com/mcp, which routes to PostHog's US or EU region. POSTHOG_MCP_URL works only for the Gemini CLI extension.

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Exploring MCP tool usage

Governed metric first

Suggested questions

Finding the tool name

How to use a per-tool tool

When to drop to SQL

Related skills

MCP connection required

Install just this skill

Install the whole plugin

Add PostHog's marketplace, then install the plugin

exploring-mcp-tool-usage

Exploring MCP tool usage

Governed metric first

Suggested questions

Finding the tool name

How to use a per-tool tool

When to drop to SQL

Related skills

MCP connection required

Install just this skill

Install the whole plugin

Add PostHog's marketplace, then install the plugin

More skills

adding-warehouse-person-properties

analyzing-expensive-users

analyzing-experiment-session-replays

assessing-heatmaps

auditing-endpoints

auditing-experiments-flags