querying-knowledge-base

Querying the Knowledge Base

Overview

Query the Powerbrain knowledge base via its MCP server. The server exposes a set of tools for semantic search, structured queries, policy checks, graph queries, and data ingestion. All requests use JSON-RPC 2.0 over HTTP POST (MCP Streamable HTTP transport).

Server

• URL: http://localhost:8080/mcp
• Transport: MCP Streamable HTTP (JSON-RPC 2.0 over HTTP POST)

Access Methods

Option A: Native MCP server (recommended)

If your agent supports MCP natively (Claude Code, OpenCode, Cursor, etc.), register the server in your agent configuration:

Claude Code (~/.claude/mcp_servers.json or project-level .mcp.json):

{
  "mcpServers": {
    "powerbrain": {
      "type": "http",
      "url": "http://localhost:8080/mcp"
    }
  }
}

OpenCode (~/.config/opencode/config.json):

{
  "mcpServers": {
    "powerbrain": {
      "type": "http",
      "url": "http://localhost:8080/mcp"
    }
  }
}

After registration, all Powerbrain tools are available directly as MCP tools — no curl required. The agent can call search_knowledge, graph_query, etc. like any other tool.

Option B: HTTP/curl (without native MCP integration)

If the agent has no native MCP support, all tools can be called via HTTP POST.

Headers: Content-Type: application/json, Accept: application/json, text/event-stream

1. Initialize (once per logical session)

curl -s http://localhost:8080/mcp -H 'Content-Type: application/json' \
  -H 'Accept: application/json, text/event-stream' \
  -d '{
    "jsonrpc": "2.0", "id": 1, "method": "initialize",
    "params": {
      "protocolVersion": "2025-03-26",
      "capabilities": {},
      "clientInfo": {"name": "agent", "version": "1.0"}
    }
  }'

2. Call a tool

curl -s http://localhost:8080/mcp -H 'Content-Type: application/json' \
  -H 'Accept: application/json, text/event-stream' \
  -d '{
    "jsonrpc": "2.0", "id": 2, "method": "tools/call",
    "params": {
      "name": "search_knowledge",
      "arguments": {
        "query": "remote work policy",
        "collection": "pb_general",
        "top_k": 5,
        "agent_id": "my-agent",
        "agent_role": "analyst"
      }
    }
  }'