ltspice-mcp

read_circuit

Read-onlyIdempotent

Extract component values, netlist content, and schematic directives from LTspice/ngspice circuit files (.cir, .net, .asc). Retrieve structured data for circuit design and verification.

Instructions

Read and parse a circuit file (.cir/.net or .asc). For netlists: returns content and component values. For schematics: returns layout and directives.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "path": "<path>"
    },
    "name": "read_circuit"
  }
}

Input Schema

Name	Required	Description	Default
`path`	Yes	Path to circuit file (.cir, .net, or .asc)
`format`	No	Response format: 'json' for structured data, 'text' for human-readable

Output Schema

Name	Required	Description	Default
`file`	No
`type`	No
`wires`	No
`labels`	No
`content`	No
`components`	No
`directives`	No
`wire_count`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Aug 21, 2026

TDQS

A4/5.0

Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnly, idempotent, and non-destructive behavior. The description adds valuable behavioral detail beyond annotations by specifying different outputs for netlists ('content and component values') versus schematics ('layout and directives'), which helps the agent predict behavior across file types.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is two sentences, front-loaded with the core action and resource, and wastes no words. Every sentence adds distinct value: the first states what it does, the second clarifies format-specific behavior.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple read-only parser, the description is largely complete given the rich annotations, fully documented schema, and existing output schema. It could have added note about unsupported file types or error behavior, but these are minor gaps for this tool's complexity.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the schema already documents both parameters fully. The description adds context about file extensions and return categories, but it does not materially improve on the parameter-level detail already present in the schema, warranting the baseline score.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description uses a specific verb ('Read and parse') and names a concrete resource ('a circuit file (.cir/.net or .asc)'), with distinct return behavior for netlists versus schematics. This clearly distinguishes it from sibling tools like create_netlist, export_netlist, and list_components.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies usage by defining what the tool reads and what it returns, but it does not explicitly state when to prefer it over alternatives or mention any exclusions. Context is present, but there is no direct 'use this instead of X' guidance despite many related sibling tools.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.