Claw Tsaver

A token-saving MCP proxy for OpenClaw users. Cuts tool call payloads by 90%+ via lazy expansion.

Why

MCP tool calls often return thousands of tokens of HTML or JSON in a single response — but the model typically uses only 5% of it. The remaining 95% silently burns context window and increases cost. claw-tsaver sits between OpenClaw and your downstream MCP servers, intercepts oversized responses, and hands the model a compact preview + an on-demand handle instead.

How

sequenceDiagram
    participant U as OpenClaw (Claude)
    participant C as claw-tsaver proxy
    participant F as fetch / puppeteer / etc.
    U->>C: call_tool("fetch", url)
    C->>F: forward call
    F-->>C: 11,507 tokens of HTML
    Note over C: tiktoken count > threshold
    C->>C: store full content in SQLite
    C-->>U: {preview_head, preview_tail, expand_handle}<br/>(only 104 tokens)
    Note over U: model decides if it needs full text
    U->>C: expand_content(handle)
    C-->>U: full 11,507 tokens

Real measurement

Test	Original tokens	Returned tokens	Saved
fetch Wikipedia "Tokenization (data security)"	11,507	104	99.1%

Tested on OpenClaw + Claude Sonnet 4.6 + mcp-server-fetch, 2026-04-25.
Raw data: benchmarks/mvp-day1-fetch.jsonl.

Quick Start

1. Prerequisites

Install uv (one-time setup):

curl -LsSf https://astral.sh/uv/install.sh | sh

No claw-tsaver install needed — uvx will fetch and run it on demand.

2. Configure downstream MCP servers

Edit ~/.claw-tsaver/config.json (first run of claw-tsaver-mcp will auto-create a template):

{
  "downstream_servers": [
    {"name": "fetch", "command": "uvx", "args": ["mcp-server-fetch"]}
  ],
  "compression_threshold_tokens": 500
}

3. Register with OpenClaw

Add this block at the top level of ~/.openclaw/openclaw.json:

"mcp": {
  "servers": {
    "claw-tsaver": {
      "command": "uvx",
      "args": ["--from", "git+https://github.com/Yang1Bai/claw-tsaver",
               "claw-tsaver-mcp"]
    }
  }
}

Then restart OpenClaw gateway: openclaw gateway restart

Dashboard

Optional: a local web UI for real-time token savings stats.

uvx --from git+https://github.com/Yang1Bai/claw-tsaver claw-tsaver-dashboard

Open http://localhost:7878 in your browser.

Roadmap

• Module A: lazy expansion proxy (this release)
• Module D: local dashboard (this release)
• Module B: tool routing (auto-load only relevant MCPs per turn)
• Module C: conversation history compression (atomic fact cards)

License

MIT — see LICENSE file.

Contributing

Issues and PRs welcome.