Model Context Protocol (MCP)
An open protocol (modelcontextprotocol.io) for wiring an LLM to external data and
tools via standardized MCP servers. The spec’s own framing is “a USB-C port for AI
applications” — one standardized connector replacing bespoke per-integration glue
(mcp-spec-introduction). It is a bridge node: it connects this wiki’s
knowledge-management cluster (A) with the agent tooling now in the sibling
agentic-tooling-wiki (B) — which is why it stays here and is linked cross-wiki.
How it actually works
From the protocol’s own architecture overview (mcp-spec-introduction):
- Client-server, one client per server. An MCP host (the AI app — Claude Code, Claude Desktop, VS Code) spins up one MCP client per MCP server; each client holds a dedicated connection. The server “provides context to MCP clients,” local or remote.
- Two layers. A data layer on JSON-RPC 2.0 (lifecycle + capability negotiation
- the primitives) over a transport layer — either stdio (local, no network overhead) or Streamable HTTP (POST + optional Server-Sent Events for remote servers; OAuth recommended). This is exactly the stdio + HTTP/OAuth surface gbrain exposes.
- Server primitives: Tools (functions the model can invoke), Resources
(context data), Prompts (reusable templates) — each discoverable via
*/list. - Client primitives (reverse direction): Sampling (a server asks the host’s LLM
for a completion, so the server can stay model-independent), Elicitation (ask the
user), and Logging. The handshake negotiates which primitives each side supports
before any work, and servers can push
list_changednotifications to keep a client’s tool registry current.
Where it shows up
- In the agent tooling (agentic-tooling-wiki): claude-financial-services uses MCP to reach 10+ data providers (Daloopa, Morningstar, FactSet, Moody’s, LSEG, …); claude-skills-ppc frames skills × MCP = agency (live Google Ads data + the ability to execute changes).
- In the knowledge-management cluster (here), qmd ships as an MCP server so an LLM can use it as a native search tool over a markdown wiki.
- gbrain exposes 30+ tools over MCP (stdio + HTTP with OAuth 2.1) to a wide range of clients (Claude Code, Cowork, Cursor, ChatGPT, Perplexity) — making it the clearest example in the wiki of MCP as the universal agent-to-knowledge interface.
Why it matters here
MCP is the common substrate beneath both clusters: the standard way an LLM agent gets access to external knowledge/tools. For the llm-wiki pattern specifically, an MCP-exposed search tool (qmd) is the recommended upgrade path once the index-file approach stops scaling.
Related
qmd · gbrain · claude-financial-services · claude-managed-agents