Privacy + injection resistance

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Router Lite MCP — deterministic prep MCP classifier

Type: local stdio · Cost: $0 · LLM: none (deterministic rules only) · Version: v0.1

SSOT docs:

• router-lite-mcp (see mcp-token-savers)/README.md — full tool spec, data policy
• your catalog config § router-lite-mcp — Pantheon catalog entry

When to use

Use router-lite-mcp when the trigger policy for prep MCPs is unclear — specifically:

• You're not sure if the task warrants vision-mcp, context-prep, retrieval-mcp, or scraper-stack
• Tuning team-wide MCP usage discipline (checking precision/recall in Pantheon)
• Building or debugging a pipeline that needs to decide which prep layer to call

Don't use on every request. Router adds latency (~30ms) and should only fire when trigger policy is genuinely ambiguous.

When NOT to use

• Trigger is obvious: cdnhwai URL = vision-mcp; local file = Read; SERP = scraper-stack
• The user gave an explicit tool instruction ("use curl for this")
• Final architecture/product/security judgment — router cannot make those calls, only frontier reasoning can

Tools

route_task

Primary tool. Given a task description, returns recommended prep MCPs + skip decision.

{
  "task": "Analyze this annotated screenshot at cdn.example.com/screenshots/abc.png and implement the UI changes",
  "context": {"input_size_chars": 1200, "has_url": true, "url_pattern": "cdn.example.com/screenshots"}
}

Returns:

{
  "recommended_mcps": ["vision-mcp"],
  "skip_mcps": ["context-prep", "retrieval"],
  "reason": "cdnhwai screenshot URL → vision-mcp prep required; no codebase question → retrieval skip; input not noisy → context-prep skip",
  "cheap_only_allowed": false,
  "confidence": 0.95
}

classify_input

Classify a raw input without routing to a specific task. Returns input type tags: screenshot_url, cdnhwai_url, log_output, spec_text, repo_question, serp_request, url_fetch.

needs_clarification

Ask whether the router needs more context to route confidently. Returns clarification questions if confidence < 0.8.

get_measurement_report

Returns aggregate metrics: calls_today, recommendations_breakdown, skip_rate, precision_estimate. Pantheon-safe export (no raw prompts/URLs/paths).

Routing logic (v0.1 deterministic rules)

Hard rule: cheap_only_allowed is always false. Frontier reasoning is mandatory for ambiguous, high-risk, architecture-heavy, security-sensitive, or final-output-sensitive work. Router only selects prep layer.

Data policy

• Request traces are metadata/count/hash only — no raw prompt text, URLs, code bodies
• Pantheon exports are aggregate-only (daily call count, recommendation breakdown, skip rate)
• Router never reads file contents or makes network calls

Proof loop

cd router-lite-mcp (see mcp-token-savers)
npm install && npm run build
npm run smoke
npm run benchmark -- --out=/tmp/router-lite-bench.json
npm run measurement:report -- --date=2026-05-03 --format=pantheon

Pantheon integration (Phase 8 roadmap)

Current: get_measurement_report returns Pantheon-safe aggregates. Planned: Pantheon Services tab (/services-usage) auto-display of router precision metrics.

Measurement report export:

{
  "date": "2026-05-03",
  "calls_total": 47,
  "vision_mcp_recommended": 12,
  "context_prep_recommended": 18,
  "retrieval_recommended": 9,
  "scraper_stack_recommended": 5,
  "all_skip": 3,
  "confidence_p50": 0.93,
  "confidence_p5": 0.72
}

Commercial comparison

Router v0.1 is boring by design — deterministic rules, zero inference cost, auditable decisions. v2 benchmark-gated for LLM routing.

SSOT cross-references

• router-lite-mcp (see mcp-token-savers)/README.md — full API spec, data policy
• your catalog config § router-lite-mcp — Pantheon entry
• configs/gatus-config.yaml § router-lite health — uptime monitoring
• the project rule (see your repo rules) — the manual version of routing rules for scraper-stack
• the project rule (see your repo rules) — the manual version of routing rules for context-prep
• the project rule (see your repo rules) — the manual version of routing rules for retrieval-mcp