List all metric names known to Prometheus, with optional substring filter.

Wraps GET /api/v1/label/__name__/values. Prometheus returns all metric names at once — no pagination. Output is capped at 500 metrics after filtering, with a truncation hint when more exist.

Use this first to discover valid metric names before writing PromQL expressions for prometheus_query or prometheus_query_range.

Examples: - Use when: "What metrics does Prometheus have about HTTP requests?" → pattern='http'; read the metrics list. - Use when: "List all node_exporter metrics" → pattern='node_'. - Use when: Starting a monitoring investigation — list metrics first to discover what's instrumented, then query specific ones. - Don't use when: You already know the exact metric name and want to query its value (call prometheus_query directly — one fewer round trip). - Don't use when: You want to see current alert state (call prometheus_list_alerts).

Returns: dict with total_count / returned_count / truncated / pattern / metrics (sorted list).

Execute an instant PromQL query against Prometheus.

Wraps GET /api/v1/query. Returns the result type (vector, scalar, matrix, string) and a list of samples each carrying labels, timestamp, and value. For vector results each element is one time series at the evaluation instant.

Examples: - Use when: "Is the payment service up right now?" → query='up{job="payment-service"}'. - Use when: "What is the current HTTP request rate?" → query='sum(rate(http_requests_total[5m])) by (job)'. - Use when: "Show me all metrics for a specific instance" → query='{instance="localhost:9090"}'. - Don't use when: You want to see how a metric changed over time (call prometheus_query_range with start/end/step). - Don't use when: You don't know the metric name yet (call prometheus_list_metrics first to discover names).

Returns: dict with query / time / result_type / result_count / data (list of samples with labels, timestamp, value).

Execute a PromQL range query returning time-series data points.

Wraps GET /api/v1/query_range. Returns one series per matching time series, each with labels and a list of [timestamp, value] pairs. Total points across all series are capped at 5000 with a truncation hint.

Prometheus may reject the query with HTTP 422 (bad_data) if the step produces too many data points (> 11,000 per series). Increase the step or narrow the time range if this happens.

Note: The Prometheus API does not support filtering by branch or commit in this endpoint — filters are expressed purely in PromQL label matchers.

Examples: - Use when: "Show me CPU usage over the last hour with 1-minute resolution" → query='rate(node_cpu_seconds_total[5m])', step='1m'. - Use when: "Graph HTTP error rate for the last 24 hours" → query='rate(http_requests_total{status=~"5.."}[5m])', start='2024-01-15T00:00:00Z', end='2024-01-16T00:00:00Z', step='5m'. - Use when: Investigating a past incident — pick the time window of the incident and use a fine step. - Don't use when: You only want the current value (call prometheus_query — faster and simpler). - Don't use when: You want alert history (call prometheus_list_alerts).

Returns: dict with query / start / end / step / result_type / series_count / total_points / truncated / data (list of series with labels, point_count, values).

List all active and pending alerts from Prometheus.

Wraps GET /api/v1/alerts. Returns every alert that Prometheus currently tracks, with labels (including alertname, severity), state (firing / pending), the time it became active, and its current value. Also returns a summary grouped by state and a count by severity label.

Examples: - Use when: "Are there any firing alerts right now?" → check firing_count and alerts where state='firing'. - Use when: "Show me all critical alerts" → filter alerts by labels.severity == 'critical'. - Use when: Checking system health during an incident — list alerts first to understand what's firing before querying metrics. - Don't use when: You want historical alert data (Prometheus stores only current state; use Alertmanager or a recording rule for history). - Don't use when: You want raw metric values (call prometheus_query or prometheus_query_range).

Returns: dict with total_count / firing_count / pending_count / state_summary / alerts (list with labels, annotations, state, active_at, value).

List Prometheus scrape targets, summarised by job and health.

Wraps GET /api/v1/targets. Returns scrape targets with job name, instance address, health status (up / down / unknown), last scrape duration in milliseconds, and any last error. Also returns a summary grouped by job and health state.

Examples: - Use when: "Which targets are currently down?" → filter targets where health='down' and check last_error. - Use when: "How many instances of the 'node-exporter' job are up?" → check job_summary for the 'node-exporter' entry. - Use when: Investigating a scrape failure — list targets for the affected job to see which instances have errors. - Don't use when: You want metric values from a target (call prometheus_query with label matchers instead). - Don't use when: You want alert status (call prometheus_list_alerts instead).

Returns: dict with state_filter / total_count / up_count / down_count / unknown_count / job_summary (per-job health counts) / targets (list with job, instance, health, last_scrape_duration_ms, last_error, labels).