MCP Resources

MCP resources are read-only data sources that clients can attach to conversations for context. Unlike tools, resources are not invoked with parameters --- they are referenced by URI and return structured data. A client might attach ltspice://status at the start of a session so the LLM knows what is available without making a tool call.

mcltspice exposes 5 resources.

ltspice://symbols

All component symbols from the LTspice library, organized by category. This is equivalent to calling list_symbols(limit=10000).

// Response structure
{
  "symbols": [
    { "name": "LT1001", "category": "Opamps", "path": "/home/user/ltspice/lib/sym/Opamps/LT1001.asy" },
    { "name": "1N4148", "category": "Misc", "path": "/home/user/ltspice/lib/sym/Misc/1N4148.asy" }
  ],
  "total_count": 6523,
  "returned_count": 6523
}

Use this when you need a complete inventory of available components. For targeted searches, the list_symbols tool with category or search parameters is more efficient.

ltspice://examples

All example circuits from the LTspice installation. Equivalent to list_examples(limit=10000).

// Response structure
{
  "examples": [
    { "name": "Buck", "category": "Educational", "path": "/home/user/ltspice/examples/Educational/Buck.asc" },
    { "name": "LT1001", "category": "jigs", "path": "/home/user/ltspice/examples/jigs/LT1001.asc" }
  ],
  "total_count": 4102,
  "returned_count": 4102
}

Examples are organized by category folder. Categories like Educational contain teaching circuits; jigs contains test and evaluation schematics for specific ICs.

ltspice://status

Current installation status as JSON. Equivalent to calling check_installation().

// Response structure
{
  "valid": true,
  "message": "LTspice installation OK",
  "paths": {
    "ltspice_dir": "/home/user/ltspice/extracted/ltspice",
    "ltspice_exe": "/home/user/ltspice/extracted/ltspice/XVIIx64.exe",
    "wine_prefix": "/home/user/ltspice/extracted/ltspice/.wine",
    "lib_dir": "/home/user/ltspice/extracted/ltspice/lib",
    "examples_dir": "/home/user/ltspice/extracted/ltspice/examples"
  },
  "lib_exists": true,
  "examples_exist": true
}

Attaching this resource at session start lets the LLM immediately know whether LTspice is ready and where files are located, without needing a tool call.

ltspice://templates

All available circuit templates (both netlist and schematic formats) with their parameters and default values.

// Response structure
{
  "netlist_templates": [
    {
      "name": "rc_lowpass",
      "description": "RC low-pass filter, fc ~ 1.59 kHz",
      "params": { "r": "1k", "c": "100n", "f_start": "1", "f_stop": "1meg" }
    },
    {
      "name": "buck_converter",
      "description": "Synchronous buck converter",
      "params": { "ind": "10u", "c_out": "100u", "r_load": "10", "v_in": "12", "duty_cycle": "0.5", "freq": "100k", "mosfet_model": "Si7336ADP", "diode_model": "CMDSH2-3" }
    }
  ],
  "schematic_templates": [
    {
      "name": "rc_lowpass",
      "description": "RC low-pass filter (.asc schematic)",
      "params": { "r": "1k", "c": "100n" }
    }
  ]
}

The response separates netlist templates (.cir files created by create_from_template) from schematic templates (.asc files created by generate_schematic). Some templates appear in both lists with slightly different parameter sets.

ltspice://template/{name}

Detail for a specific template by name. This is a URI template --- replace {name} with the template name.

Example URIs:

ltspice://template/rc_lowpass
ltspice://template/buck_converter
ltspice://template/sallen_key_lowpass

// Response for ltspice://template/rc_lowpass
{
  "name": "rc_lowpass",
  "netlist": {
    "description": "RC low-pass filter, fc ~ 1.59 kHz",
    "params": { "r": "1k", "c": "100n", "f_start": "1", "f_stop": "1meg" },
    "type": "netlist (.cir)"
  },
  "schematic": {
    "description": "RC low-pass filter (.asc schematic)",
    "params": { "r": "1k", "c": "100n" },
    "type": "schematic (.asc)"
  }
}

If the template exists in only one format (netlist or schematic), only that key is present. If the template name is not found, the response contains an error field:

// Response for unknown template
{
  "error": "Template 'nonexistent' not found"
}