MCP Agora

MCP Server with cross-agent persistent memory for AI agent fleets.

Agora is a local, Python-only MCP server that gives your AI agents (Claude Code, Codex, ChatGPT, Gemini CLI) a shared persistent memory. Knowledge saved by one agent is immediately available to all others — no more repeating work, no more isolated sessions.

uv run agora

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Features

Features

Phase 1 — Core Memory

• agora_save — Save knowledge with semantic embeddings (tags optional)
• agora_query — Semantic search across all saved knowledge (top-k results)
• agora_status — Server stats: memory count, agents, cache, backends, health, DB size
• Persistent ChromaDB storage (data survives restarts)
• L1 in-memory cache (TTLCache, 1000 entries, 5min TTL, full-param SHA-256 cache key)
• Cache invalidation on save (clear-all L1+L2, safe strategy)
• Fully local embeddings (sentence-transformers all-MiniLM-L6-v2, 384d, no API key)
• Background warmup (model loads in daemon thread, server starts instantly)
• WarmingUpError grace (tools return friendly message if model not yet loaded)

Phase 2 — Routing & Backend Connectors

• agora_route — Route tool calls to external MCP servers by name or semantic match
• agora_broadcast — Call a tool on ALL backends in parallel via asyncio.gather
• agora_backends — List configured backends with connection status
• Semantic router — Routes to backends via cosine similarity on description embeddings (threshold >= 0.5)
• Exact-name router — Case-insensitive exact match tried first, falls back to semantic
• STDIO connector — Subprocess MCP client via stdio_client + ClientSession, lazy connection on first use
• HTTP connector — Streamable HTTP MCP client for remote servers
• BackendRegistry — Lifecycle management: register from config, lazy connect, disconnect_all on shutdown
• Config-driven backends — Declare external MCP servers in config.yaml with env var expansion (${GITHUB_TOKEN})
• GitHub MCP — Pre-configured: issues, PRs, repos, code search, commits
• Playwright MCP — Pre-configured: browser automation (navigate, click, screenshot), read_only

Phase 3 — Cross-agent Memory

• agora_crossref — Cross-reference entries by query or entry_id (groups by agent)
• agora_forget — Delete entries by ID, tags, or agent (supports dry_run)
• SQLite provenance — Who saved what, when, with what confidence
• L2 persistent cache — SQLite-backed, 24h TTL, survives restarts
• 3-tier cache cascade — L1 (TTLCache) → L2 (SQLite) → ChromaDB

Phase 4 — Robustness

• Health check — Backend health monitoring (healthy/unhealthy/dead with 3-failure threshold)
• Configurable retry — Per-backend max_retries + retry_delay
• Rate limiting — Per-backend rate_limit_rps to prevent API abuse
• Structured logging — File-based logging to ~/.agora/logs/agora.log (configurable via LOG_LEVEL)
• Non-blocking startup — Background warmup thread + WarmingUpError grace on embedding-dependent tools
• 6 graceful degradation tests — Backend failure, health cascade, retry, rate limit
• 61 tests across 10 files, all passing

Planned (Phase 5)

Feature	Description
Quickstart in 3 comandi	One-liner install + run
Config YAML fully commented	Every line explained
GitHub release	Tagged release, changelog
PyPI publication	pip install mcp-agora
PDF architecture diagram	Visual diagram replacing ASCII

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Architecture

┌────────────────────────────────────────────────────┐
│                   TRANSPORT LAYER                   │
│               STDIO (JSON-RPC 2.0)                  │
├────────────────────────────────────────────────────┤
│                   PROTOCOL LAYER                     │
│       tools/list · tools/call · resources/list      │
├────────────────────────────────────────────────────┤
│                   ROUTER LAYER (Fase 2)             │
│   ┌──────────┐  ┌──────────┐                        │
│   │ Semantic │  │  Static  │                        │
│   │  Router  │  │  Router  │                        │
│   └────┬─────┘  └────┬─────┘                        │
│        └──────────────┘                              │
├───────────────────────┴────────────────────────────┤
│                   MEMORY LAYER                       │
│   ┌────────────────────────────────────────────┐    │
│   │  VECTOR INDEX (ChromaDB)                   │    │
│   │  Collection: "knowledge"                    │    │
│   │  384d embeddings, cosine similarity         │    │
│   └────────────────────────────────────────────┘    │
├────────────────────────────────────────────────────┤
│                   CACHE LAYER                        │
│   ┌────────────────────────────────────────────┐    │
│   │  L1: TTLCache (memory, 5min TTL, 1k max)   │    │
│   │  L2: SQLite    (disk,  24h TTL,  10k max)  │    │
│   └────────────────────────────────────────────┘    │
├────────────────────────────────────────────────────┤
│                BACKEND CONNECTORS (Fase 2)           │
│   ┌──────────┐ ┌──────────┐ ┌──────────┐            │
│   │ STDIO    │ │ HTTP     │ │ Custom   │            │
│   └──────────┘ └──────────┘ └──────────┘            │
├────────────────────────────────────────────────────┤
│                  EMBEDDING LAYER                     │
│   sentence-transformers (all-MiniLM-L6-v2, 384d)     │
└────────────────────────────────────────────────────┘

---

Quickstart

One-liner install

# Unix (Linux / macOS)
curl -fsSL https://raw.githubusercontent.com/cioffiAI/mcp-agora/main/scripts/install.sh | sh

# Windows (PowerShell)
iwr -useb https://raw.githubusercontent.com/cioffiAI/mcp-agora/main/scripts/install.ps1 | iex

Manual install

# Prerequisites: Python 3.13+ and uv 0.11+
#   Unix:  curl -LsSf https://astral.sh/uv/install.sh | sh
#   Windows: irm https://astral.sh/uv/install.ps1 | iex

# Install from PyPI
uv tool install mcp-agora

# Run
agora

From source

git clone https://github.com/cioffiAI/mcp-agora.git
cd mcp-agora
uv run agora

Configure as MCP Server

Add to your MCP host config (e.g. opencode.jsonc):

{
  "mcp": {
    "agora": {
      "type": "local",
      "command": ["uv", "run", "--directory", "/path/to/mcp-agora", "agora"],
      "enabled": true
    }
  }
}

Usage

# Save knowledge
uv run python -c "
from agora.server import create_server
"  # or use via MCP tools in your agent

Via MCP tools (in any MCP-compatible agent):

Save:

Call tool: agora_save
  content: "PostgreSQL BRIN indexes are useful for very large tables with correlated data"
  tags: ["postgres", "sql", "performance"]
→ { "saved": true, "id": "mem_20260505_..." }

Query:

Call tool: agora_query
  query: "PostgreSQL indexing performance"
  top_k: 5
→ { "query": "...", "results": [...], "cached": false }

Status:

Call tool: agora_status
→ { "server": "Agora", "memory_entries": 42, "cache_stats": {...}, "backends": {...} }

Route to backend:

Call tool: agora_route
  target: "github"
  tool: "github_search_repositories"
  arguments: { "query": "mcp server" }
→ { "target": "github", "matched_by": "exact_name", "result": { "items": [...] } }

List backends:

Call tool: agora_backends
→ { "backends": [{ "name": "github", "connected": false, "tool_count": 15, ... }] }

---

Configuration

Default config.yaml (v0.4.0):

agora:
  name: "Agora"
  version: "0.4.0"

storage:
  chroma_path: "~/.agora/chroma"
  db_path: "~/.agora/agora.db"

cache:
  l1_max_entries: 1000
  l1_ttl_seconds: 300
  l2_max_entries: 10000
  l2_ttl_seconds: 86400

embedding:
  provider: "sentence-transformers"
  model: "all-MiniLM-L6-v2"

backends:
  - name: "github"
    transport: "stdio"
    command: ["npx", "-y", "@modelcontextprotocol/server-github"]
    description: "GitHub API: issues, PRs, repos, code search, commits"
    read_only: false
    timeout_seconds: 15
    max_retries: 3
    retry_delay: 1.0
    rate_limit_rps: 5
    env:
      GITHUB_TOKEN: "${GITHUB_TOKEN}"
  - name: "playwright"
    transport: "stdio"
    command: ["npx", "@playwright/mcp@latest"]
    description: "Browser automation: navigate, click, screenshot, forms"
    read_only: true
    timeout_seconds: 30
    max_retries: 2
    retry_delay: 0.5
    rate_limit_rps: 2

Override config path: AGORA_CONFIG=/path/to/config.yaml uv run agora

---

Testing

# All tests
uv run pytest tests/ -v

# Single test
uv run pytest tests/test_cache.py -v -k "test_hit_count"

# MCP smoke tests (real STDIO subprocess)
uv run pytest tests/test_mcp_smoke.py -v

61 tests across 10 files:

File	Count	Scope
test_embedding.py	3	Dimension, vector format, document retrieval order
test_memory.py	5	ChromaDB add, query, delete, multiple docs, integration
test_cache.py	5	TTLCache set, get, expiry, hit_count, clear
test_l2_cache.py	7	L2 SQLite set, get, expiry, hit_count, stats, clear, prune
test_provenance.py	7	Agent registry, provenance add/get/list/delete
test_protocol.py	6	FastMCP tool wiring, save→query, cache hit, provenance
test_routing.py	9	Cosine similarity, exact/semantic/no match, warmup
test_connectors.py	8	Properties, health, disconnect, read-only enforcement
test_graceful.py	6	Backend failure, health cascade, retry, rate limit
test_mcp_smoke.py	5	Full smoke, multiple entries, stress, routing, status

---

Project Structure

mcp-agora/
├── pyproject.toml              # Dependencies, build config, entry point
├── config.yaml                 # Server configuration (incl. backends)
├── README.md                   # This file
├── AGENTS.md                   # Agent-facing instructions
├── ARCHITECTURE.md             # Full architecture, rationale, risk analysis
├── agora/
│   ├── main.py                 # Entry point: `agora` command
│   ├── server.py               # FastMCP server + tool registration
│   ├── config.py               # YAML config loader (incl. BackendConfig)
│   ├── logging.py              # File-based structured logging
│   ├── registry.py             # BackendRegistry (lifecycle, lazy connect)
│   ├── connectors/
│   │   ├── __init__.py
│   │   ├── base.py             # BackendConnector ABC + ReadOnlyBlockedError
│   │   ├── stdio.py            # STDIO subprocess MCP client
│   │   └── http.py             # Streamable HTTP MCP client
│   ├── routing/
│   │   └── router.py           # Semantic + exact name router
│   ├── embedding/
│   │   ├── base.py             # Abstract EmbeddingProvider + WarmingUpError
│   │   └── sentence.py         # sentence-transformers wrapper
│   ├── memory/
│   │   └── vector_store.py     # ChromaDB PersistentClient wrapper
│   ├── cache/
│   │   ├── l1_memory.py        # TTLCache in-memory
│   │   └── l2_cache.py         # SQLite-backed persistent cache
│   └── db/
│       └── database.py         # SQLite: agents, provenance, L2 cache
├── tests/
│   ├── test_embedding.py
│   ├── test_memory.py
│   ├── test_cache.py
│   ├── test_l2_cache.py
│   ├── test_provenance.py
│   ├── test_protocol.py
│   ├── test_routing.py
│   ├── test_connectors.py
│   ├── test_graceful.py
│   ├── test_mcp_smoke.py
│   └── _echo_server.py         # Minimal FastMCP echo server for tests
└── examples/
    └── config.yaml.example

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Stack

Component	Technology
Runtime	Python 3.13+, uv 0.11+
MCP Framework	FastMCP (mcp SDK ≥1.0.0)
Vector Store	ChromaDB (PersistentClient, HNSW index)
Embeddings	sentence-transformers all-MiniLM-L6-v2 (384d), lazy-load + background warmup
Cache L1	cachetools TTLCache (1k entries, 5min TTL)
Cache L2	SQLite (10k entries, 24h TTL)
Provenance	SQLite (agents, entry provenance)
Config	PyYAML (env var expansion $VAR)
Testing	pytest, pytest-asyncio

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License

MIT