Use Synth with AI assistants via the Model Context Protocol — configuration and available tools.

MCP Server

Synth ships a Model Context Protocol (MCP) server that exposes every compiler stage as a tool for AI agents. Agents can validate designs, apply auto-fixes, search the component registry, import parts, and export to KiCad — all without leaving their tool surface.

Supported Transports

The MCP server supports two transports:

Transport	Command	Use case
stdio	`synth mcp --stdio`	AI agent harnesses (Claude Desktop, Antigravity IDE, Cursor) — recommended
HTTP + SSE	`synth mcp --sse --port 3000`	Custom agents and scripts via HTTP

Available MCP Tools

Design & validation

Tool	What it does
`synth_language_reference`	Returns the full SynthSpec grammar plus three complete example designs. Call this first when drafting a `.synth` file from scratch.
`synth_validate`	Validate a SynthSpec file; returns structured diagnostics.
`synth_fix`	Apply suggested fixes from diagnostics back to the source.
`synth_export`	Export a validated design to a KiCad project.
`synth_place`	Run PCB placement and return the placement IR.
`synth_route`	Run placement + routing and return the routing IR.

Component registry

Tool	What it does
`synth_search_registry`	Keyword search the local Tier-1 + Tier-2 registries.
`synth_search_registry_web`	Keyword search LCSC/EasyEDA for live stock and pricing. Falls back to the local registry when offline.
`synth_import_part`	Import a part from LCSC (`source: "lcsc"`), a KiCad symbol (`source: "kicad"`), or a SnapEDA/UltraLibrarian zip (`source: "kicad-zip"`).
`synth_author_part`	Validate and persist a hand-authored TOML part definition.

Configuration

Add the following to your AI assistant's MCP settings:

Claude Desktop

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

{
  "mcpServers": {
    "synth": {
      "command": "synth",
      "args": ["mcp", "--stdio"]
    }
  }
}

Cursor / other editors

Add a mcp section to your editor's settings (see your editor's MCP documentation for the exact location). The command is synth mcp --stdio.

[!TIP] Running from a checkout? Replace "synth" with the path to the built binary:
"command": "/path/to/synth/target/debug/synth"

The Agent Design Loop

A typical agent workflow for designing a new board:

1. synth_language_reference   → get the SynthSpec grammar + examples
2. synth_search_registry      → find part IDs and pin names
3. [draft board.synth]
4. synth_validate             → check for errors
5. synth_fix                  → auto-apply suggested fixes
6. synth_search_registry_web  → verify parts are in stock
7. synth_export               → generate the KiCad project

Troubleshooting

The assistant says it can't find synth

Make sure the synth binary is on your system PATH:

which synth        # macOS / Linux
where synth        # Windows

If not found, see the Quick Start Guide for build instructions.

Debug the MCP server

Run the server manually to see its output:

synth mcp --stdio

Or use SSE mode with logging:

synth mcp --sse --port 3000

MCP Server

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