nuthatch
Documentation MCP server

MCP server

The protocol reference for the built-in Model Context Protocol server. For the experience - wiring an agent up in one step and what it can do - see AI-native → Agent-grade MCP.

Transport

nuthatch mcp serves MCP over stdio, bridging to a running nuthatch dev HTTP API (--url, default http://127.0.0.1:8288). The bridge is a thin client of the same guarded endpoints described in the HTTP API reference - an agent gets no capability a curl doesn’t have. nuthatch mcp --print-config prints a copy-paste client config (a Claude Code .mcp.json plus the claude mcp add one-liner) and exits.

Tools

The eight generic tools below are advertised on every nest. The capability-gated ones are advertised only where they will return data (RFC-0025): balance/top_balances where the nest has a transfer-shaped decoder, and flags/exposure where compliance is configured.

  • status - index status: contract, chain, rows indexed, holders, last and sealed block.
  • schema - the data model: how tables and views are named and queried. Read this first.
  • tables - every decoded table ({alias}__{event}) with columns, Solidity types, and topic0.
  • table (name, limit = 50) - recent rows of one table, hot ∪ sealed.
  • sql (query, limit = 200) - a read-only query over the live tip ∪ sealed history. SELECT/WITH only; returns a compact table plus a provenance stamp. The bridge passes a small row cap so an agent’s context isn’t flooded.
  • explain (query) - validate a query without executing it; returns {valid: true} or an error with a fix hint. Cheaper than sql - check before you spend.
  • entity (id) - one row by id ({block:012}-{logindex:06}).
  • diff (from + to, or block, or tx with its block; flow, top, final_only) - what happened in that range as a JSON document of fixed sentences with exact amounts, the same bytes as nuthatch diff --format json and GET /diff. flow: true gives the token flow instead; final_only refuses a range above the sealed boundary, and top above 1,000 is refused. Since 5.9.0.
  • balance (address) / top_balances (limit) - derived balances from the IVM view (i128 base units as decimal strings).
  • flags (kind) - threshold or velocity compliance flags (RFC-0008).
  • exposure (address) - counterparty exposure to the labeled set, per label.

Resources

Three read-only resources an MCP client can attach as context:

  • nuthatch://schema (text/plain) - the composed schema document.
  • nuthatch://tables (application/json) - the table list.
  • nuthatch://status (application/json) - the index summary.

Prompts

Three server-side prompts encode the known-good workflows. investigate-address is advertised only where compliance is configured, like the tools it names:

  • profile-contract - an activity overview of the indexed contract(s), starting from schema.
  • investigate-address (address) - balances, exposure and flags for one address.
  • verify-a-number (claim) - re-derive a figure from scratch, with provenance.

Everything is local: the server talks only to your own nest, and nothing phones home.

Checked against Nuthatch 5.11.0 (2026-10-23). Verify a release-specific command with the CLI reference before running it in production.