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analyzing-experiment-query-performance

Pull and interpret production experiment query-performance data from the staff-only `/api/debug_ch_queries` endpoints backing the `/experiments/staff` scene: slowest experiment queries, precompute read/build health, and preaggregation cache footprint. Covers prod-US and prod-EU via a `query_performance:read` personal API key, all query params, and response field semantics (exception codes, exposure paths, precompute skip reasons, job states). Use when investigating slow or failing experiment queries, precompute regressions, 307/159/241 errors, preaggregation table growth, or when asked how experiment query performance or the precompute rollout is doing in production.

78

Quality

98%

Does it follow best practices?

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The risk profile of this skill

SKILL.md
Quality
Evals
Security

Quality

Content

96%Weight 40%Scale 1-5

Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.

A strong, self-contained operational skill: every section carries non-obvious production knowledge, all guidance is executable, and the investigation workflow includes explicit healthy-baseline validation and branch logic. The only structural gap is that the detailed API reference is entirely inlined rather than split into a reference file.

DimensionReasoningScore

Conciseness

The body is dense with non-generic operational knowledge (INTERNAL-scope key rejection, TTL-jitter partition spread, stale_failed/stuck_pending semantics, skip-reason interpretation) and contains no padding or explanations of concepts Claude already knows; it even adds token-efficiency guidance ('save to a file and project fields with jq; don't stream the raw body into the transcript'). Every token earns its place for this domain.

5 / 5

Actionability

Fully executable throughout: a copy-paste browser-devtools snippet for key creation, export commands, a both-region curl loop with an env-var guard, concrete jq projections, complete parameter tables, and 403 troubleshooting. The examples cover the common investigation cases directly.

5 / 5

Workflow Clarity

The 5-step Investigation workflow has an explicit healthy-baseline checklist ('failed reads a small fraction of total... stale_failed/stuck_pending at zero'), a conditional branch ('anything off → slowest_queries with a targeted filter'), an escalation path to the Metabase skill, and a reproducibility citation requirement. It is a read-only diagnostic workflow, so the destructive-operation cap does not apply.

5 / 5

Progressive Disclosure

Sections are well organized with clear headers and the cross-references that do exist (Metabase skill, backend/frontend source files) are clearly signaled with no nesting. However, the full endpoint and field-semantics API reference (~120 lines) is inlined with no bundle files at all, where a one-level-deep reference file could slim SKILL.md — a minor organization gap rather than the ideal split.

4 / 5

Total

19

/

20

Passed

Description

100%Weight 40%Scale 1-5

Based on the skill's description, can an agent find and select it at the right time? Clear, specific descriptions lead to better discovery.

The description is a model example: concrete capabilities, an explicit 'Use when' clause with natural trigger terms including specific error codes, and a tightly scoped niche. Third-person voice throughout with no fluff or over-claims.

DimensionReasoningScore

Specificity

Names multiple concrete actions with comprehensive coverage: 'Pull and interpret production experiment query-performance data', 'slowest experiment queries, precompute read/build health, and preaggregation cache footprint', plus 'all query params, and response field semantics (exception codes, exposure paths, precompute skip reasons, job states)'. No coverage gaps of the 4 anchor remain.

5 / 5

Completeness

Explicitly answers both questions: a clear 'what' (pull and interpret query-performance data, three analysis areas, params, field semantics, both regions, the read scope) followed by an explicit 'Use when...' clause with concrete trigger phrases — a direct match to the 5 anchor.

5 / 5

Trigger Term Quality

Natural trigger phrases a user would actually say: 'slow or failing experiment queries', 'precompute regressions', '307/159/241 errors', 'preaggregation table growth', 'how experiment query performance or the precompute rollout is doing in production' — including raw error codes users would quote verbatim.

5 / 5

Distinctiveness Conflict Risk

A clear niche with distinct triggers: staff-only /api/debug_ch_queries endpoints, the query_performance:read scope, prod-US/EU, and precompute-specific vocabulary. Minimal overlap risk with any other skill.

5 / 5

Total

20

/

20

Passed

Validation

100%

Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.

Validation — 16 / 16 Passed

Validation for skill structure

No warnings or errors.

Repository

PostHog/posthog

Path

.agents/skills/analyzing-experiment-query-performance/SKILL.md

Reviewed

Table of Contents

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