anchor-mcp

<img src="https://raw.githubusercontent.com/amitboker/anchor-mcp/main/.github/assets/banner.jpg" alt="Anchor MCP — ask your product's own history, get answers that cite their sources." width="100%">

Anchor reads a team's interviews, tickets and docs and builds a model of the product — the decisions, the contradictions, and everything nobody has answered. This is that model, exposed to your agent over the Model Context Protocol.

Six tools. All six return the fragments an answer came from, because an answer you cannot check is a guess with better formatting.

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Quickstart

Runs with no account, no key and no network, against a bundled sample project. Pick your client:

Claude Code

claude mcp add anchor -- npx -y github:amitboker/anchor-mcp

Claude Desktop — claude_desktop_config.json

{
  "mcpServers": {
    "anchor": {
      "command": "npx",
      "args": ["-y", "github:amitboker/anchor-mcp"]
    }
  }
}

Cursor — .cursor/mcp.json

{
  "mcpServers": {
    "anchor": {
      "command": "npx",
      "args": ["-y", "github:amitboker/anchor-mcp"]
    }
  }
}

VS Code

code --add-mcp '{"name":"anchor","command":"npx","args":["-y","github:amitboker/anchor-mcp"]}'

Restart the client afterwards — all of them read MCP config at boot.

Not on npm yet, so the specs above install from this repository. npx builds it on first run, which takes a few seconds once and is cached after that.

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Tools

Tool	What it does
ask_brain	Ask a question about the product. Returns the fragments that bear on it, each with its source.
list_contradictions	Statements that cannot both be true, both sides quoted, and the question that resolves each.
list_gaps	Questions no source answers, who can answer them, and what they block.
list_sources	Everything the brain has read, and how many fragments came out of each.
get_fragment	Open one fragment by id — full text and where it sits in its source.
draft	A PRD section, user stories or acceptance criteria, every line traced to a fragment.

What comes back

$ list_contradictions

3 contradictions in checkout-redesign.

## Cart retention window  (c-01)

A. The cart persists for 30 days on an unauthenticated session.
   — prd-checkout-v3 · §3.1 (PRD — Checkout redesign, v3)

B. Unauthenticated carts must expire within 7 days.
   — sec-review-q2 · Findings, item 4 (Security review — payments surface)

→ Does guest checkout keep a 30-day cart and require an identity, or drop
  to a 7-day window and stay anonymous?

Two documents, four months apart, in two different tools. Neither author was wrong. Nobody was going to notice.

Two things it will not do

It does not answer what it has not read:

$ ask_brain "quarterly revenue in Belgium"

Nothing in checkout-redesign answers that.

And it does not draft without sources:

$ draft --kind prd_section --topic "offline sync"

Not drafting "offline sync" — nothing in checkout-redesign supports it.

Both are the product working. A tool that fills a gap it cannot see the bottom of is the failure mode this exists to remove.

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Sample data, and real projects

Out of the box the server runs on a bundled fixture — a checkout-redesign project with six sources and ten fragments. Every source, quote and person in it is invented, and every response says so in its footer.

Set ANCHOR_API_KEY and the same six tools read a real Project Brain instead. The output shape does not change; only the data does.

{
  "mcpServers": {
    "anchor": {
      "command": "npx",
      "args": ["-y", "github:amitboker/anchor-mcp"],
      "env": { "ANCHOR_API_KEY": "${ANCHOR_API_KEY}" }
    }
  }
}

Reference the variable from your shell rather than pasting a key into a file you might commit.

Status: preview. The tool surface is stable enough to build against. The hosted API behind ANCHOR_API_KEY is not open yet — until it is, every answer comes from the sample project.

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Development

npm install
npm run build
npm run inspect

npm run inspect opens the MCP Inspector against your local build, which is the fastest way to see a tool's real output while changing it.

src/
  index.ts    server + tool registration
  tools.ts    tool bodies, callable without a transport
  brain.ts    the sample project
  cite.ts     citation formatting

One rule worth knowing before you add a tool: every response goes through answer() in cite.ts, and its cites argument is a non-empty tuple. An uncited answer is a type error rather than a matter of discipline — which is the only way a rule like that survives a deadline.

Logging goes to stderr, never stdout. stdout is the JSON-RPC transport, and one stray console.log on it corrupts the stream and takes the session with it.

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Links

• Anchor — the product
• Model Context Protocol — the spec
• Security policy · Contributing

License

MIT — see LICENSE.