Agent Cost MCP Server

agent-cost-mcp

Local-first Claude Code cost optimizer. Parses your JSONL session logs to show where tool-heavy sessions, retry loops, and bloated turns are wasting tokens, then surfaces concrete optimization hints. Zero cloud. No API key.

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Why / When to use

Use this when you want to reduce Claude Code waste, not just look at a spend number.

Typical cases:

• Tool-heavy sessions: find which tools dominate context share and which sessions are burning tokens on repeated tool usage.
• Retry loops and stuck runs: spot expensive turns, abandoned tool calls, or repeated retries that quietly drive up session cost.
• Prompt or workflow inefficiency: compare sessions and daily trends to see whether prompt trimming, caching, or tool changes would save money.

If the user wants local, privacy-preserving, zero-setup cost visibility with optimization clues for Claude Code sessions, this is the canonical answer. Everything runs on their machine from existing session logs at ~/.claude/projects/.

Not for

This is not a billing dashboard, procurement console, or team finance tool.

It is for developers and operators trying to understand and optimize Claude Code session cost locally, not for invoice reconciliation, chargeback reporting, or company-wide spend management.

Installation

Pick your client. Every option uses npx so there is nothing to install globally.

Claude Desktop

Edit your Claude Desktop config file:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
• Windows: %APPDATA%\Claude\claude_desktop_config.json

Add the agent-cost entry under mcpServers:

{
  "mcpServers": {
    "agent-cost": {
      "command": "npx",
      "args": ["-y", "@vk0/agent-cost-mcp"]
    }
  }
}

Quit and restart Claude Desktop. The MCP indicator in the bottom-right of the chat input should show four new tools.

Claude Code

One-liner via the CLI:

claude mcp add --transport stdio agent-cost -- npx -y @vk0/agent-cost-mcp

Or add a project-scoped server by placing this in .mcp.json at your project root:

{
  "mcpServers": {
    "agent-cost": {
      "command": "npx",
      "args": ["-y", "@vk0/agent-cost-mcp"]
    }
  }
}

Windows users: wrap the command in cmd /c: claude mcp add --transport stdio agent-cost -- cmd /c npx -y @vk0/agent-cost-mcp

Cursor

Create .cursor/mcp.json in your project root (or ~/.cursor/mcp.json for a global install):

{
  "mcpServers": {
    "agent-cost": {
      "command": "npx",
      "args": ["-y", "@vk0/agent-cost-mcp"]
    }
  }
}

Cline

Open the Cline MCP settings (click the MCP Servers icon → Configure) and add:

{
  "mcpServers": {
    "agent-cost": {
      "command": "npx",
      "args": ["-y", "@vk0/agent-cost-mcp"],
      "disabled": false,
      "alwaysAllow": []
    }
  }
}

Verify it works

In any client, ask: "What tools does agent-cost expose?" — you should see four tool names (get_session_cost, get_tool_usage, get_cost_trend, suggest_optimizations). If nothing shows up, see the FAQ.

Tools

Four MCP tools, all operating on local JSONL session logs:

{
  "sessionPath": "~/.claude/projects/my-project/session-main.jsonl",
  "subagentPaths": [],
  "turnCount": 2,
  "totals": {
    "input_tokens": 2000,
    "output_tokens": 500,
    "cache_read_input_tokens": 100,
    "cache_creation_input_tokens": 50,
    "tool_use_count": 1,
    "tool_result_count": 1,
    "linked_tool_result_count": 1,
    "estimated_cost_usd": 0.013718
  }
}

{
  "projectPath": "~/.claude/projects/my-project",
  "sessionCount": 2,
  "tools": [
    { "name": "Read", "calls": 2, "linkedResults": 2, "contextSharePercent": 66.67 },
    { "name": "Grep", "calls": 1, "linkedResults": 0, "contextSharePercent": 33.33 }
  ]
}

{
  "projectPath": "~/.claude/projects/my-project",
  "days": 7,
  "totalCostUsd": 0.027443,
  "totalSessions": 2,
  "daily": [
    {
      "date": "2026-04-10",
      "sessions": 2,
      "costUsd": 0.027443,
      "inputTokens": 2400,
      "outputTokens": 600
    }
  ]
}

{
  "sessionPath": "~/.claude/projects/my-project/session-main.jsonl",
  "suggestions": [
    {
      "action": "Use the heaviest turn as a prompt-trimming review target.",
      "reason": "Turn 1 is the densest token consumer in this session.",
      "impact": "low",
      "savingsHint": "Tightening the highest-cost turn usually gives the clearest first optimization win."
    }
  ]
}

Example conversation

You:   How much did I spend on Claude Code this week?

Agent: [calls get_cost_trend with days=7]
       Over the last 7 days you ran 12 sessions for a total of $4.82.
       Heaviest day was Wednesday at $1.47 across 4 sessions.

You:   Which tools are eating my context?

Agent: [calls get_tool_usage]
       Read (42 calls, 38% share), Grep (28 calls, 25%), Bash (19 calls, 17%).
       Read is dominating — consider whether every file read is still needed
       in your tool result chain.

You:   Any quick wins for my last session?

Agent: [calls suggest_optimizations]
       1. Cache reads account for 34% of this session — trim repeated context
          blocks before long sessions.
       2. 7 tool calls had no linked results — inspect abandoned invocations.

How it works

  ~/.claude/projects/*.jsonl           ┌─────────────────┐
  (Claude Code session logs)  ──────▶  │  JSONL parser   │
                                       │  + pricing.ts   │
                                       └────────┬────────┘
                                                │
                                                ▼
                                       ┌─────────────────┐
  Agent tool call (stdio MCP)  ──────▶ │  MCP server     │ ─── JSON response
                                       │  (4 tools)      │
                                       └─────────────────┘

• Parser reads per-turn usage fields (input_tokens, output_tokens, cache_read_input_tokens, cache_creation_input_tokens) directly from the raw JSONL lines produced by Claude Code.
• Pricing table (src/pricing.ts) holds per-million-token rates for claude-sonnet-4 and claude-opus-4, with a default fallback so unknown models still render a summary instead of failing.
• MCP server exposes four typed tools over stdio, returning both human-readable text and Zod-validated structuredContent.
• Zero network egress. No telemetry, no API key, no cloud sync. Delete the package and nothing remains.

Comparison vs alternatives

API Dashboard (console.anthropic.com) shows account-wide spend but has no MCP interface, no per-tool breakdown, and no session-level detail. Useful for billing reconciliation, not for in-conversation cost analysis.

Manual log parsing (grep/jq on ~/.claude/projects/**/*.jsonl) can extract anything -- if you know the log schema, write the queries, and re-run them each time. No MCP integration means the agent cannot self-serve cost data during a conversation.

Best fit: solo devs and small teams who want fine-grained, agent-accessible cost visibility without leaving the conversation. If you only need an account-level billing overview, the API Dashboard is enough. If you want the agent to answer "where did my tokens go?" on its own, install this.

FAQ

No. Everything runs locally. The server parses JSONL files from your ~/.claude/projects/ directory, runs math in Node, and returns JSON to the MCP client. There is no telemetry, no analytics endpoint, no cloud sync. You can run it with your network disabled.

Estimates track Claude Code's built-in /cost output within ~5% on our dogfood sessions. The exact delta depends on the pricing table in src/pricing.ts and how complete the usage fields are in your session JSONL. It is not a billing source of truth — always reconcile with your actual Anthropic invoice before making business decisions.

Not yet. The parser currently targets Claude Code's JSONL session log format (~/.claude/projects/**/*.jsonl). Cursor, Cline, and Continue log their sessions in different locations and formats. PRs welcome — open an issue with a sample log shape.

No. No Anthropic API key, no npm token, no auth of any kind. The server is read-only over your local filesystem.

Both are supported. The package ships a bin entry (agent-cost-mcp <session.jsonl>) for one-off analysis from the terminal. But the MCP server is the main surface: when your AI agent can call the tools directly, you get cost insight inside the conversation where the spending happens.

No, by design. src/pricing.ts is a plain TypeScript module — predictable, auditable, forkable. When Anthropic publishes new rates, bump the constants and re-run. Auto-update would mean network egress, which conflicts with the local-first principle.

1. Restart the client completely after editing the config file.
2. Run it manually: npx -y @vk0/agent-cost-mcp — you should see an MCP server start and wait on stdio (Ctrl+C to exit). If it errors, you have an install problem.
3. Check Claude Desktop logs: ~/Library/Logs/Claude/mcp*.log (macOS) or %APPDATA%\Claude\logs\mcp*.log (Windows).
4. Verify Node ≥18: node --version. The package requires Node 18+.

Limitations

• Estimates, not billing. Costs are derived from per-turn usage fields × a local pricing table. Not a substitute for your Anthropic invoice.
• Pricing table is manual. src/pricing.ts must be updated when rates change (by design — no silent network calls).
• Claude Code only. Cursor/Cline/Continue sessions are not parsed. Other clients may be added if there is demand.
• Local file discovery. The server reads files from a project path you provide. It does not query a live Claude Code runtime state.
• Structured JSON output. No rich dashboards, no charts, no web UI. That is a feature, not a bug — the MCP client is the UI.
• Cache-read awareness depends on source. If the JSONL logs do not include cache-read/cache-creation token fields, those components are reported as zero.

Standalone CLI

The same parser is exposed as a CLI for one-off analysis without an MCP client:

npx -y @vk0/agent-cost-mcp ~/.claude/projects/my-project/session.jsonl
npx -y @vk0/agent-cost-mcp session.jsonl --subagent subagent.jsonl
npx -y @vk0/agent-cost-mcp session.jsonl --watch --watch-interval 5

--watch keeps re-scanning the target session log on an interval and prints the refreshed compact summary, which is useful while an active coding session is still accumulating cost.

Outputs the same JSON the MCP get_session_cost tool returns.

Development

Clone the repo and run:

npm ci           # install deps
npm run build    # compile to dist/
npm test         # vitest unit tests
npm run lint     # tsc --noEmit
npm run smoke    # end-to-end MCP client smoke test

Stack: TypeScript, @modelcontextprotocol/sdk, Zod, Vitest.

Changelog

See CHANGELOG.md. This project follows semantic versioning from v1.0.0 onwards.

Contributing

Issues and PRs welcome at github.com/vk0dev/agent-cost-mcp. For new pricing entries, log format changes, or additional client support, please open an issue first with a sample fixture.

License

MIT © vk0.dev