MCP Server for Claude Desktop — Search Your Local Files

What people do with it

Three workflow patterns where searching local files inside a Claude conversation collapses hours of work into minutes.

For compliance officers and audit teams

The pain. Pulling together every email, KYC update, and flagged transaction tied to a single customer takes four to six hours per case. The information lives across SharePoint exports, your local archive of past investigation files, and folders that — for regulatory reasons — cannot leave the building.

The setup. Point LocalSynapse at your compliance archive and your case folders. Add LocalSynapse to your Claude Desktop config. Nothing leaves the machine. Required by retention policy and consistent with most audit standards.

What it looks like.

Claude Desktop

Summarize all communications, KYC updates, and flagged transactions for customer 7842 between January and December 2024. Cite the source file for each item.

Found 12 communications, 3 KYC updates, and 5 flagged transactions for customer 7842. Structured summary with citations below.

case_7842_2024Q1.emlkyc_review_2024.pdftxn_flagged_log.xlsx

Claude calls LocalSynapse over MCP, retrieves the relevant snippets from the indexed corpus, and produces a structured summary with citations back to the original files. You verify against the source files, which are linked inline. Twenty minutes per case instead of four hours.

4 hours20 min

For technical writers and product managers

The pain. Your product has shipped a dozen versions across three years. When a customer asks "did the authentication flow change between v3.2 and v3.4?" the answer is buried across release notes, deprecated docs, internal RFC documents, and a few Confluence pages everyone forgot about.

The setup. Index your documentation repository, your release notes archive, and an exported dump of Confluence or Notion. Add LocalSynapse to Claude Desktop, Claude Code, or Cursor — same MCP server, any client.

What it looks like.

Claude Desktop

Show me every place we describe the authentication flow, grouped by product version. Highlight what changed between v3.2 and v3.4.

8 passages describe the authentication flow across v3.0 → v3.4. Key diff between v3.2 and v3.4: token rotation moved from refresh-on-use to fixed-window.

release_v3.4.mdrfc_042_auth.mdconfluence_auth_dump.html

Claude pulls the relevant passages, organizes them by version, and surfaces the diff in prose. Half a day of doc archaeology becomes five minutes of focused review.

half a day5 min

For independent consultants and solo practitioners

The pain. Three years of proposals, scoping docs, slide decks, and final reports — across roughly thirty clients. When a new lead asks "have you worked on something similar?" you spend two hours guessing filenames and opening folders, hoping to find the right precedent.

The setup. Point LocalSynapse at your entire client archive. Add it to Claude Desktop.

What it looks like.

Claude Desktop

Find the three past projects most similar to a B2B SaaS supply-chain optimization engagement. Pull the most relevant slide from each, with the file path.

Three closest matches to a B2B SaaS supply-chain engagement. Most relevant slide pulled from each, with file paths.

Acme_SCM_Proposal_2023.pdfsupply_chain_phase1.pptxlogistics_final_q3.docx

Claude searches semantically across decks and proposals, surfaces the closest matches, and quotes the relevant passages with file paths. Five minutes. The new pitch starts from real precedent, not a blank deck.

2 hours5 min

30-second setup

Three steps. No login. No cloud account. No telemetry.

Install LocalSynapse

Download the installer for Windows or macOS. Run it. Choose the folders you want indexed.

Download →

Add LocalSynapse to your Claude Desktop config

Open your Claude Desktop config file and add this entry under mcpServers:

{
  "mcpServers": {
    "localsynapse": {
      "command": "C:\\Program Files\\LocalSynapse\\LocalSynapse.exe",
      "args": ["mcp"]
    }
  }
}

Config file location:
Windows: %APPDATA%\Claude\claude_desktop_config.json
macOS: ~/Library/Application Support/Claude/claude_desktop_config.json

Restart Claude Desktop

Quit Claude Desktop completely and reopen it. LocalSynapse will appear in the MCP server list. You're ready.

Do I have to keep the app open?

No. Claude Desktop launches the connector itself, as its own process, using the command in the config above. You never have to open the LocalSynapse window, and closing it does not affect Claude.

·The connector is not a child of the app window. Quitting the app — or never opening it — leaves Claude's access intact.
·It starts when your MCP client starts and exits when the client exits. There is no daemon to manage and no port to open; the two talk over standard input and output.
·Several clients can use it at once. Claude Desktop and another agent can both hold a connection, and each gets full search including semantic results.
·Indexing is separate. Whichever process is running keeps the index up to date, and exactly one of them does that work at a time, so two clients cannot index the same files twice.

This changed in 2.18.0. Before that the connector really was a child of the app window, and closing the window took it down with it — which meant leaving a full desktop app resident just to keep an AI agent working. If you are on an older build, updating is the fix.

What LocalSynapse exposes over MCP

Nine tools, designed to be composable. Any MCP client can call them.

search_files

Search inside your documents by keyword or by meaning. Returns documents with passages under them — several excerpts per document, each carrying its position — plus a `request` block stating how the query was read and what was left unconstrained, so the caller can correct the interpretation and ask again.

get_file_content

Read the extracted text of up to 20 indexed files in one call, by file id. Each id comes back exactly once with a status, so a partial result is never silently a whole one.

list_indexed_files

Browse what is indexed, filtered by folder or extension. Useful for orientation — "what do we actually have?" — before searching for something specific.

get_pipeline_status

Check indexing coverage: what has been scanned, extracted and embedded, and what is still queued. Worth calling before trusting an empty result.

get_email_thread

Walk a mail conversation up and down the reply chain from any message in it, returning the messages in order.

get_spreadsheet

Read a spreadsheet as structure rather than flattened text — cell coordinates, sheet names and merged ranges preserved, with the cell's declared type honoured rather than guessed.

get_timeline

Reconstruct what happened around a period or a topic: file versions, related mail and the order they occurred in.

get_work_session

Group the files and messages that belong to one stretch of work, so an agent can pick up context rather than isolated hits.

preview_index_removal

Show exactly what would be removed from the index before anything is removed. A dry run, not an action.

Built on the official MCP C# SDK. All tools work with any MCP-compatible client.

Works with

Claude Desktop

Primary integration. The setup snippet above is for Claude Desktop.

Claude Code

Anthropic's terminal coding agent. Same MCP server, same config pattern.

Cursor

Code editor with native MCP support.

Cline

VS Code extension with MCP support.

Any MCP client

MCP is an open protocol. LocalSynapse works with any client that speaks it.

Don't see your client? If it speaks MCP, it works. Open an issue →

What stays on your machine

The whole point.

All indexing is local.

Embeddings run on your CPU through ONNX Runtime. The model is downloaded once at first run and used offline thereafter.

The MCP server uses stdio.

LocalSynapse does not open a network port. Claude Desktop launches it as a child process and talks to it over standard input and output. No HTTP, no socket, no daemon.

Free tier sends no data.

A small anonymous version ping is sent only on user-initiated update check. Every other byte stays put. See the full disclosure.

Give Claude Desktop a local memory.

What people do with it

30-second setup

Install LocalSynapse

Add LocalSynapse to your Claude Desktop config

Restart Claude Desktop

Do I have to keep the app open?

What LocalSynapse exposes over MCP

Works with

Claude Desktop

Claude Code

Cursor

Cline

Any MCP client

What stays on your machine

All indexing is local.

The MCP server uses stdio.

Free tier sends no data.

Start searching with Claude.

Give Your AI Agent a Local Memory: MCP Server for File Search