Berry

What it does

Berry is an MCP server designed for workflow verification, allowing AI agents to detect hallucinations and audit execution traces. It transforms uncited LLM outputs into evidence-backed results by providing a system to track spans and verify claims.

Tools

• detect_hallucination: Analyzes model output to identify potential hallucinations using token logprobs.
• audit_trace_budget: Monitors and audits the trace budget for verification tasks.
• start_run: Initiates a new evidence notebook run.
• load_run: Loads an existing run for analysis.
• add_span: Adds a new span of evidence to the current run.
• list_spans: Lists all spans associated with a run.
• search_spans: Searches through existing evidence spans.

Installation

Add the following to your claude_desktop_config.json:

{
  "mcpServers": {
    "berry": {
      "command": "berry",
      "args": []
    }
  }
}

Note: Requires running pipx install -e . and berry init in your repository first.

Supported hosts

Cursor, Codex, Claude Code, Gemini CLI