AgentCorp-Inc 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.
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.
Suggested questions
Lead with these when the user is unsure what to ask:
| 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 |
| "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 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
The tools cover the per-tool drill-downs and the harness cut. For cross-tool
rankings (the tool-quality matrix), custom breakdowns, session listing, or
per-session tool calls, query $mcp_tool_call directly with posthog:execute-sql
— the schema and recipes are in
models-mcp.md.
Related skills
exploring-mcp-tool-quality— rank tools by error rate / latency / reach, then drill inexploring-mcp-sessions— a single agent run and its tool sequenceexploring-mcp-intent-clusters— agent goals grouped by semantic similarity