@airmcp-dev/meter

7-layer call classification and metrics collection for MCP servers.

Installation

npm install @airmcp-dev/meter

Meter is also included in @airmcp-dev/core as middleware. The standalone package adds advanced features.

MeterConfig

interface MeterConfig {
  enabled?: boolean;          // Default: true
  classify?: boolean;         // 7-layer auto-classification (default: true)
  trackCalls?: boolean;       // Call tracking (default: true)
  trackTokens?: boolean;      // Token usage tracking (default: false)
  budget?: {
    dailyLimit?: number;
    monthlyLimit?: number;
    maxTokensPerCall?: number;
    onExceed?: 'warn' | 'block';
  };
}

7-Layer classification

Layer	Matching patterns	Description
L1	ping, health, version, echo	Static response
L2	get, read, find, lookup, list, show	Simple lookup
L3	convert, transform, format, parse, encode, decode	Data transformation
L4	compute, calculate, aggregate, analyze, summarize	Aggregation (default)
L5	fetch, request, call_api, webhook, http, post, put, delete	External API
L6	generate, complete, chat, embed, infer, predict	LLM call
L7	agent, think, plan, execute, reason, chain, orchestrate	Agent chain

Unmatched tools default to L4. Override with defineTool's layer property.

API

getMetricsSnapshot()

function getMetricsSnapshot(): {
  totalCalls: number;
  successRate: number;              // 0–1
  avgLatencyMs: number;
  layerDistribution: Record<'L1'|'L2'|'L3'|'L4'|'L5'|'L6'|'L7', number>;
  toolCounts: Record<string, number>;
};

resetMetricsHistory()

function resetMetricsHistory(): void;

Internal storage

Ring Buffer (max 10,000 records). O(1) push, oldest records auto-evicted. Constant memory usage.

interface CallRecord {
  tool: string;
  layer: 'L1' | 'L2' | 'L3' | 'L4' | 'L5' | 'L6' | 'L7';
  latencyMs: number;
  success: boolean;
  timestamp: number;
}

→ Meter guide