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MCP Slim Guard v0.1.1-alpha.1 — Self-service Alpha

MCP Slim Guard v0.1.1-alpha.1 — Self-service Alpha Pre-release
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@lennney lennney released this 31 Jul 20:33
v0.1.1-alpha.1
0812db2

76% fewer MCP tokens in our standard benchmark

Up to 99.7% in synthetic stress testing

Same upstream call. Exact recovery.

MCP Slim Guard reduces Tool catalogs on its Generic surface and eligible
oversized results on its Generic and Native surfaces. This release adds a
reversible self-service path for Codex and Claude Code.

The exact standard fixture reduced normal-path tokens from 71,388 to 17,007
(76.18%) across 24/24 tasks with 24 upstream calls. The 99.71% result is a
synthetic 100-Tool, 8,000-row stress-test upper bound, not an expected rate.

What is new

  • Measure before installation. analyze lists Tools and estimates catalog
    size without writing a file or invoking a Tool.
  • Preview the Host change. plan --host codex|claude-code prints the exact
    proposal without writing it.
  • Install with a backup. install applies and validates one bounded Host
    configuration change.
  • Inspect local delivery evidence. profile --last reads bounded audit
    metadata without reading result bodies or invoking upstream.
  • Restore the earlier configuration. rollback refuses to overwrite later
    user edits.

Runtime contract

authorize -> bind exact Tool -> execute upstream once
          -> pass through or project + snapshot
          -> read_result retrieves the snapshot

Codex uses the Native surface with authorized original Tool names plus
read_result. Claude Code uses the Generic find_tool, call_tool, and
read_result surface.

Projection starts only after the upstream result exists. Structured, mixed,
error, schema-bound, source-like, and uncertain results pass through. A
projection, storage, observation, or audit failure returns the exact upstream
result.

Install

npm install -g mcp-slim-guard@alpha
cd /absolute/path/to/your-project

mcp-slim-guard analyze
mcp-slim-guard init
mcp-slim-guard validate
mcp-slim-guard plan --host codex
mcp-slim-guard install --host codex --json
mcp-slim-guard profile --last
mcp-slim-guard rollback --host codex --json

Use --host claude-code for Claude Code. Read the
Host setup guide
before replacing an existing Host entry.

Proof

Path Normal-path tokens Tasks Upstream calls
Direct MCP 71,388 24/24 24
Slim Guard 17,007 24/24 24

The standard fixture uses o200k_base and makes no model or API calls. It does
not measure model answer quality, provider caching, billing, or a universal
savings rate.

Read the
benchmark method
and
stress-test evidence.

Host compatibility

Host Alpha status Surface
Codex Supported Native preferred; Generic fallback
Claude Code Supported Generic
VS Code Preview only Native configuration preview
OpenCode Post-Alpha Not released

Current limits

The Alpha handles MCP Tool catalogs and Tool results over local stdio. It does
not compress conversation history, provider prompts, source files, MCP prompts
or resources, or every result shape. Recovery references belong to the current
runtime generation.

Release artifact

npm: https://www.npmjs.com/package/mcp-slim-guard/v/0.1.1-alpha.1
source tag: v0.1.1-alpha.1
tarball bytes: 155899
SHA-1: 2fbdbddf9565432d2b88c9d589c5440534d062cd
SHA-256: 8f2887b5dfb81bb91223476c7047c252d4aba99ae5f41d38513a217c0860651f
integrity: sha512-Y1n5puYTfaaEK7kMcrk88fCk9DnQux6x18Fjm0RKkYo7k8bkae53dwBmCiGlGVnohDTTO2JBM0q3btrCJkTclw==

Feedback

Try one Host and MCP Server pair you rely on. Report the exact versions,
transport, result shape, and recovery outcome:

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v0.1.0 — First Public Release

v0.1.0 — First Public Release Latest
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@lennney lennney released this 31 Jul 20:33
v0.1.0
38fb7c8

mcp-slim-guard v0.1.0

The control plane between AI agents and MCP servers.

Reclaim ~83% of MCP tool-schema context without changing your existing servers — and verify the result yourself.

Key Features

  • 5-level schema compression — off/light/normal/extreme/maximum, plus lazy loading
  • Security pipeline — glob-based allow/deny → SSRF protection → injection detection (17 patterns) → rate limiting (Token Bucket) → audit logging
  • STDIO + HTTP transport — works with Claude Code, Cursor, Codex, and any MCP client
  • SIGHUP hot reload — zero-downtime config changes
  • Audit logging — Pino JSON output with file rotation and gzip compression
  • Request caching — TTL+LRU memory cache for read-only tool calls
  • Schema stats in CLI — transparent character count + estimated token count
  • Benchmark suite — 4 modules: tokens, schema, latency, accuracy

Quick Start

npm install -g mcp-slim-guard
mcp-slim-guard init
mcp-slim-guard validate
mcp-slim-guard start

Stats

  • 402 tests, 20 test files
  • 5 production dependencies
  • Node.js ≥ 18
  • MIT License
Assets 2
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