Skip to main content
Glama
circuitjs-mcp

circuitjs-mcp

by Suzu-Gears

circuitjs-mcp

Falstad CircuitJS1 回로 시레이터를 AI 에이전트에서 조작할 수 있게 하는 MCP 서버입니다. 표준 stdio MCP 서버이므로 Claude Code, Codex CLI, Claude Desktop, Cursor 등 MCP 지원 클라이언트라면 어디서든 사용할 수 있습니다.

CircuitJS1이란 Paul Falstad 씨의 회로 시뮬레이터——예전에는 Java 애플릿 버전 "Circuit Simulator Applet" 으로 친숙했고, 현재는 falstad.com/circuit 에서 브라우저에서 동작하는 것——의 HTML5/JavaScript 버전 이름입니다. 브라우저의 Java 애플릿 지원 종료에 따라 Iain Sharp 씨가 GWT로 JavaScript에 포팅했으며, 시뮬레이션 엔진도 회로 텍스트 형식도 애플릿 버전과 공통입니다(애플릿 시대의 회로 파일을 그대로 읽을 수 있습니다). 본 서버가 이용하는 JavaScript 인터페이스는 CircuitJS1이 된 이후 추가된 기능으로, 애플릿 버전에는 없습니다.

컴파일된 CircuitJS1 웹앱(webapp/에 포함, 오프라인 동작)을 헤드리스 Chromium(Playwright) 안에서 기동하고, 그 JavaScript 인터페이스를 MCP 도구로 공개합니다. 시뮬레이터 상태는 도구 호출을 넘어 유지됩니다(회로 읽기 → 실행 → 측정 → 회로 재작성을 대화식으로 할 수 있습니다).

셋업

전제: Node.js 18 이상.

cd circuitjs-mcp
npm install          # postinstall で Playwright の Chromium も入ります
npm test             # スモークテスト(RC回路の過渡応答が理論値と一致するか等を検証)

playwright install chromium이 환경상 어려운 경우에는 기존 Chrome/Chromium을 사용할 수 있습니다:

export CIRCUITJS_CHROMIUM="/usr/bin/google-chrome"   # 例

Related MCP server: circuit-sim-mcp

MCP 클라이언트에 등록

시작 명령은 모든 클라이언트에서 동일합니다: node /絶対パス/circuitjs-mcp/server.mjs

환경 변수 CIRCUIJS_HEADFUL=1를 붙이면 브라우저 창이 표시되고, 사라도 에이전트와 같은 시레이터를 직접 조작할 수 있습니다(공동 작업 모드). 아래 예시는 모두 이 변수가 붙은 상태입니다. 필요 없으면 떼 주세요.

Claude Code:

claude mcp add circuitjs -e CIRCUITJS_HEADFUL=1 -- node /絶対パス/circuitjs-mcp/server.mjs

Codex CLI:

codex mcp add circuitjs --env CIRCUITJS_HEADFUL=1 -- node /絶対パス/circuitjs-mcp/server.mjs

설정 파일 방식 클라이언트(Claude Desktop의 claude_desktop_config.json, Cursor의 mcp.json 등):

{
  "mcpServers": {
    "circuitjs": {
      "command": "node",
      "args": ["/絶対パス/circuitjs-mcp/server.mjs"],
      "env": { "CIRCUITJS_HEADFUL": "1" }
    }
  }
}

screenshot 도구는 MCP의 이미지 콘텐츠로 PNG를 반환합니다. 이미지 표시를 지원하지 않는 클라이언트에서는 save_path 인수로 파일에 저장하는 방식으로 사용해 주세요.

도구 목록

기능

circuit_load

Falsad 텍스트 형식의 회로를 읽어 들임(검증 포함). 요소 목록을 반환

circuit_state

시각 · 모든 요소의 전압 차/전류/단자 전압, 라벨이 붙은 노드의 전압을 획득

run_transient

지정 시뮮레이션 시간만큼 실행하고, 프로브(노드 전압 · 요소 전류/전압/전력)의 시계열을 샘플링하여 반환

sim_control

run / stop / reset / status, 최대 타임스텝 설정, 외부 전압원 값 설정

circuit_export

회로를 Falstad 텍스트 또는 SVG로 내보내기

circuit_link

현재 회로(또는 지정 텍스트)를 falstad.com에서 그대로 열 수 있는 URL(?ctz= 링크)로 생성. 브라우저에서 대화식으로 확인·편집하고 싶을 때

screenshot

현재 회로도의 PNG 스크린샷(이미지로 반환, 파일 저장도 가능)

eval_js

위 도구로 부족한 조작용 탈출구. sim 객체에 대해 임의의 JS를 실행

사용 예(에이전트에 대한 지시 예시)

  • "1kΩ와 1µF의 RC 로우패스를 만들어 1kHz 구형파를 넣었을 때의 출력 파형을 5ms분 가져와"

  • "이 회로(텍스트 붙여넣기)를 읽어 들여 각 저항의 소비 전력을 목록으로 만들어 줘"

  • "회로 스크린샷을 보여 줘"

측정하고 싶은 곳에는 라벨이 붙은 노드(요소 타입 207, 예: 207 336 128 400 128 4 out)를 두면 {"node":"out"} 프로브나 circuit_state의 nodes로 전압을 읽을 수 있습니다. 요소 단위의 전류·전압은 circuit_load / circuit_state가 반환하는 index로 지정합니다.

스크립트에서 직접 조작

MCP 클라이언트를 거치지 않고 스크립트에서 도구를 호출하고 싶다면 drive.mjs를 사용할 수 있습니다. 서버를 자식 프로세스로 기동하고, 명령 디렉터리에 둔 JSON 파일(cmd-1.json, cmd-2.json, ...)을 차례로 실행하여 결과를 res-N.json에 씁니다:

node drive.mjs /tmp/cjs-commands
# 別プロセスから: echo '{"tool":"circuit_state","args":{}}' > /tmp/cjs-commands/cmd-1.json

파일은 임시 이름으로 쓴 다음 rename으로 배치할 것(쓰기 도중 읽기를 피하기 위해).

환경 변수

변수

의미

CIRCUITJS_CHROMIUM

사용할 Chrome/Chromium 실행 파일의 경로(기본: Playwright 관리의 Chromium. 실패 시 시스템 Chrome으로 폴백)

CIRCUITJS_URL

내장 webapp 대신 읽어 들일 CircuitJS1의 URL(예: https://www.falstad.com/circuit/circuitjs.html)

CIRCUITJS_HEADFUL

1이면 브라우저 창을 표시(디버그용)

제한 사항

  • run_transient의 시뮬레이션 속도는 회로의 $ 행의 시뮬레이션 속도 설정과 CPU에 의존합니다. 실제 시간이 너무 오래 걸리면 wallTimeoutMs로 중단되고, 부분 데이터가 반환됩니다(reason 필드로 판별 가능).

  • 회로의 "편집"은 Falstad 텍스트를 다시 써서 circuit_load를 다시 하는 것이 기본입니다(가져오기 시 시각은 리셋됩니다).

  • 과도 해석만(CircuitJS1 자체가 AC 소신호 해석 등을 가지지 않기 때문). 주파수 특성은 주파수를 바꿔 가며 run_transient를 반복하면 얻을 수 있습니다.

라이선스

본 리포지토리 전체를 GPL-2.0-or-later로 제공합니다(COPYING.txt).

  • CircuitJS1은 Paul Falstad / Iain Sharp의 GPLv2+ 소프트웨어입니다. webapp/는 그 컴파일된 빌드(무수정)이며, 대응하는 소스 코드는 pfalstad/circuitjs1(원작) 및 code4fukui/circuitjs1의 pages 브랜치(본 빌드의 취득원)에서 입수할 수 있습니다.

  • 서버 코드(server.mjs, drive.mjs, test-client.mjs) © 2026 Suzu(涼鈴), GPL-2.0-or-later.

Available Tools

8 tools
circuit_exportExport circuitB

Export the current circuit as Falstad text format, or as an SVG drawing of the schematic.

NameRequiredDescriptionDefault
formatNoDefault "text".

TDQS

B3.4/5.0
Behavior3/5

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

With no annotations, the description must carry the behavioral context. It clearly indicates the tool produces either Falstad text or SVG, but it does not disclose whether the export returns content directly, creates a file, or has any side effects. Some useful behavior is stated, but meaningful context is missing.

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 a single, well-structured sentence that conveys the tool's purpose and its two output formats without redundancy. Every word contributes meaning.

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

Completeness3/5

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

The tool is simple, with one optional parameter, so extensive documentation is not required. However, since there is no output schema, the description does not clarify what the tool returns or how the exported content is delivered, leaving some ambiguity for an agent.

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

Parameters4/5

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

While the schema already documents the 'format' enum and default, the description enriches the enum values by explaining that 'text' means Falstad text format and 'svg' means a drawing of the schematic. This adds value beyond the bare parameter name and enum list.

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

Purpose4/5

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

The description names a specific verb ('Export'), the resource ('the current circuit'), and two concrete output formats ('Falstad text format' or 'SVG drawing'). It is clear and informative, though it does not explicitly distinguish itself from sibling tools like screenshot or circuit_link.

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

Usage Guidelines2/5

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

There is no guidance about when to choose this tool over alternatives such as screenshot or circuit_link. The description states what it does but not in what situations it is preferred, nor what it is not for.

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

circuit_loadLoad circuitA

Replace the current circuit with the given circuit definition in Falstad CircuitJS1 text format (the same format produced by File > Export as Text, starting with a "$" line). Resets simulation time to 0. Returns the list of parsed elements so you can verify the circuit and note element indices for probing. The simulator keeps state between tool calls.

NameRequiredDescriptionDefault
runNoStart the simulation running after load (default false).
textYesCircuit in Falstad text format. First line is the "$" options line: `$ flags timestep simSpeed currentSpeed voltageRange powerScale minTimestep`. A reasonable default: "$ 1 0.000005 10.20027730826997 50 5 50 5e-11". Coordinates are grid-snapped multiples of 16.

TDQS

A4.3/5.0
Behavior4/5

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

No annotations are provided, so the description carries the full burden. It discloses key side effects: replacing the current circuit, resetting simulation time to 0, keeping simulator state across calls, and returning parsed elements for verification. This goes beyond the bare schema and gives the agent useful behavioral expectations.

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?

Three purposeful sentences cover action, input format, side effects, return value, and state persistence. The core operation is front-loaded, and there is no filler or repetition.

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

Completeness5/5

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

For a moderately simple load tool with no output schema, the description covers the required input format, reset behavior, return value, and cross-call statefulness. Combined with a fully described schema, an agent has enough to call it correctly and interpret the result.

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%, and the schema already explains the text format, the '$' line, reasonable defaults, and the run boolean. The tool description adds no parameter-specific meaning beyond noting the returned element list, so the baseline score of 3 applies.

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?

States the operation (replace), the exact resource (current circuit), the input format (Falstad CircuitJS1 text starting with a '$' line), and the return value. This stands apart from siblings such as circuit_export and circuit_state, so an agent can select it correctly.

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

Usage Guidelines4/5

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

Clear that this tool is for installing a new circuit definition and that simulator state persists across calls, implying use at circuit-setup/load time. It does not explicitly name alternatives or say when not to use it, but no sibling has an overlapping function, so the gap is small.

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

circuit_stateRead circuit stateA

Read the current simulation state: time, running flag, timestep, and every element with its voltage difference, current, post voltages and info string. Use the element index values with run_transient probes. Optionally pass node names (of labeled nodes, e.g. from "207 ..." labeled-node elements) to read their voltages.

NameRequiredDescriptionDefault
nodesNoLabeled node names to read voltages for.

TDQS

A4.2/5.0
Behavior4/5

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

No annotations are provided, so the description carries the full behavioral burden. It clearly frames the operation as a non-mutating read and lists what will be reported. It does not disclose potential edge cases such as behavior when the simulation is not running or the possibility of very large output, but it is generally transparent for a read-only state inspection tool.

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 three sentences, each serving a distinct purpose: stating the primary behavior, linking to run_transient usage, and explaining the optional parameter. There is no redundancy or filler, and the most important information is front-loaded.

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 tool with one optional parameter, the description covers the returned data, the source of valid node labels, and a cross-tool usage hint. Minor gaps such as output formatting, units, or error behavior are absent, but these are not critical for correctly invoking this tool.

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

Parameters4/5

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

The input schema has 100% description coverage, providing a baseline of 3. The description adds value beyond the schema by explaining that acceptable node names are labeled nodes and giving a concrete provenance example ('207 ...' labeled-node elements). It also clarifies the optional nature of the parameter.

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 states a clear read operation on the current simulation state and enumerates the specific data returned: time, running flag, timestep, and per-element voltage difference, current, post voltages, and info string. The verb 'read' and the explicit data inventory distinguish it from the write/control siblings in the context.

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 provides a concrete usage hint: use returned element index values with run_transient probes. It also explains when to pass labeled node names. However, it does not explicitly state when to prefer circuit_state over siblings like circuit_load or sim_control, nor does it give any when-not-to-use guidance.

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

eval_jsEvaluate JavaScript against the simulatorA

Advanced escape hatch: run arbitrary JavaScript inside the CircuitJS1 page. The code is the body of an async function receiving sim (the CircuitJS1 object, see https://www.falstad.com/circuit/doc/js-interface.html). Return a JSON-serializable value. Example: "return sim.getElements().filter(e => e.getType()==='ResistorElm').map(e => e.getCurrent())".

NameRequiredDescriptionDefault
codeYes

TDQS

A4.3/5.0
Behavior4/5

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

With no annotations, the description carries the transparency burden. It clearly explains the execution model: code becomes an async function body, receives the `sim` object, and must return a JSON-serializable value. It does not spell out side effects or error behavior, but the phrase 'run arbitrary JavaScript' strongly implies mutating potential.

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?

Two sentences plus one example carry high information density with no filler. The core operational facts are front-loaded, and the example earns its place by clarifying the expected code shape.

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?

The description covers how to invoke the tool, what the code receives, the return contract, and links to the simulator's documented interface. It lacks explicit caveats about side effects or serialization failures, but given the tool's arbitrary-code nature and the provided example, an agent has enough to call it correctly.

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

Parameters5/5

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

The single `code` parameter is fully elaborated despite 0% schema description coverage. The description defines what the code should look like, what context it receives, what it must return, and provides a practical example. This fully compensates for the schema's minimal parameter definition.

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 names a specific verb and resource: run arbitrary JavaScript inside the CircuitJS1 page. The 'advanced escape hatch' framing and concrete example clearly distinguish it from the sibling tools, which are more specialized operations.

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?

Usage context is only implied by 'Advanced escape hatch,' suggesting it is a fallback when the standard tools cannot express the needed operation. It does not explicitly state when not to use it or name any sibling alternatives for common cases.

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

run_transientRun transient simulationA

Run the simulation for a given amount of SIMULATED time while sampling probes, then stop. Returns time-series data {t, }. Probes: {"node":"name"} reads a labeled node voltage; {"element":i,"quantity":"current"|"voltageDiff"|"power"} reads element i (indices from circuit_state/circuit_load). Simulation speed is bounded by the circuit's sim-speed setting and CPU, so wall-clock time may differ from simulated time; the call aborts with partial data if wallTimeoutMs elapses first.

NameRequiredDescriptionDefault
probesYes
secondsYesSimulated seconds to run, e.g. 0.01.
fromResetNoReset the circuit to t=0 first (default true).
maxSamplesNoMax samples to return (default 500).
wallTimeoutMsNoWall-clock abort, default 30000, max 120000.

TDQS

A4.2/5.0
Behavior4/5

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

With no annotations, the description must carry the behavioral burden, and it does: it explains that simulation stops after the target time, returns partial data if wallTimeoutMs is hit, and that wall-clock can differ from simulated time. It does not explicitly describe side effects on circuit state beyond what fromReset implies, but the disclosure is still substantial.

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 tightly structured: first sentence states the core operation, second defines the output and probe syntax, third explains timing behavior. Every sentence earns its place, and the key scoping constraint (SIMULATED time) is front-loaded.

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 tool with five parameters, no annotations, and no output schema, the description is largely complete: it covers probe semantics, return shape, timeout behavior, and the sim-speed relationship. It could add a bit more detail about the exact output format or default reset behavior, but these are at least hinted at or covered by the schema.

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

Parameters4/5

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

Schema coverage is 80%, so some parameter meaning is already provided. The description adds real value by defining probe syntax and semantics: node probes read labeled voltage, element probes read current/voltageDiff/power with indices from circuit_state/circuit_load. This goes beyond the bare schema and compensates for the harder-to-infer parameters.

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 states a specific action ('Run the simulation'), the resource (a transient simulation), and the core distinguishing scope (simulated time with probe sampling). It also identifies the return type as time-series data, so it is clear how this tool differs from siblings like circuit_load or circuit_state.

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 gives useful context, including how probe indices relate to circuit_state/circuit_load and how sim-speed affects wall-clock time. However, it never explicitly states when to prefer this tool over an alternative or what would be a better tool for a different task, such as sim_control.

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

screenshotScreenshot the schematicA

Take a PNG screenshot of the circuit as currently drawn (including scope traces if the circuit defines scopes). Returns the image; optionally also saves it to save_path.

NameRequiredDescriptionDefault
save_pathNoAbsolute file path to also save the PNG to.

TDQS

A4.1/5.0
Behavior4/5

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

With no annotations, the description carries the full behavioral disclosure burden. It states that the tool returns a PNG image, optionally saves it to save_path, and includes scope traces only when scopes are defined. It does not mention file-overwrite behavior, but the core side effects are transparent.

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 a single front-loaded sentence that conveys the primary action, the return value, the inclusion condition, and the optional parameter without redundancy. Every clause contributes useful information.

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

Completeness5/5

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

For a simple one-optional-parameter capture tool with no output schema, the description fully explains what is returned and the only optional side effect. An agent has enough information to invoke the tool correctly.

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%, and the description only restates what the schema already says about save_path ('optionally also saves it to save_path'). No additional parameter meaning is added beyond the schema's explicit 'Absolute file path to also save the PNG to.'

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 opens with a specific verb and resource ('Take a PNG screenshot of the circuit as currently drawn') and clarifies the included content ('including scope traces if the circuit defines scopes'). This clearly distinguishes the tool from siblings like circuit_export and circuit_load.

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 use for capturing the current visual circuit state and notes when scope traces are included, but it never explicitly states when to use this tool versus alternatives such as circuit_export. Usage context is present only by implication.

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

sim_controlControl simulationB

Start/stop/reset the simulation, set the max timestep, or set the voltage of an external voltage source (an "Extern voltage" element, type ExtVoltageElm, addressed by its name). "reset" reloads the current circuit, zeroing time and all state.

NameRequiredDescriptionDefault
actionNo
extVoltageNo
maxTimeStepNoSeconds, e.g. 5e-6.

TDQS

B3.1/5.0
Behavior3/5

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

With no annotations provided, the description carries the behavioral disclosure burden. It usefully discloses reset semantics ('reloads the current circuit, zeroing time and all state'), but does not explain side effects of run/stop, whether operations block, or what status returns.

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

Conciseness4/5

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

The description is a single, front-loaded sentence that conveys the primary actions efficiently. The parenthetical detail about external voltage elements is somewhat dense but adds necessary precision without redundancy.

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

Completeness2/5

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

The description omits the 'status' action entirely even though it appears in the schema enum. It also provides no return-value information, no constraints on combining parameters, and no mention of prerequisites, which is significant for a control tool with no output schema and no annotations.

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 low at 33%, and the description partially compensates by explaining extVoltage as an external voltage source element addressed by name. However, the action enum values have no accompanying behavioral descriptions, and maxTimeStep relies on the schema's unit example.

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

Purpose4/5

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

The description clearly identifies the tool's purpose: starting, stopping, resetting the simulation, setting max timestep, and setting external voltage source values. It uses specific verbs and a named resource, though it does not explicitly differentiate itself from siblings like run_transient.

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

Usage Guidelines2/5

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

The description provides no explicit guidance on when to use this tool versus alternatives such as run_transient. The action enum implies some usage, but there are no stated conditions, exclusions, or selection criteria.

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

Tool Schema Changelog

Recent tool additions, removals, and schema changes observed during successful MCP inspections.

  1. 8 tool updatesv1.0.0
    • First observedcircuit_export
    • First observedcircuit_link
    • First observedcircuit_load
    • First observedcircuit_state
    • First observedeval_js
    • First observedrun_transient
    • First observedscreenshot
    • First observedsim_control

TDQS

A3.9/5.0

Scored across 8 tools

Disambiguation5/5

Each tool has a clear, distinct role: loading/exporting circuits, reading state, controlling simulation, running transient probes, taking screenshots, generating links, and escaping to JS. circuit_state and run_transient are separated clearly as snapshot vs. time-series sampling.

Naming Consistency3/5

Four tools use the circuit_ prefix, while sim_control, run_transient, screenshot, and eval_js follow different patterns. The names are still readable, but the convention is not uniformly applied across the server.

Tool Count5/5

Eight tools is a well-scoped count for a circuit simulator server. Each tool maps to a meaningful user need without redundancy or bloat.

Completeness5/5

The set covers the full simulation workflow: load, export, inspect, control, run transient analysis, capture output, and share. eval_js provides an escape hatch for anything not explicitly exposed, leaving no obvious dead ends.

Related MCP Connectors

Related MCP Servers

  • A
    license
    Not graded
    quality
    D
    maintenance
    Generates, simulates, and inspects LTspice circuits via MCP tools and resources, providing structured JSON interfaces for AI agents.
    MIT
  • F
    license
    Not graded
    quality
    F
    maintenance
    Provides circuit simulation capabilities via MCP, enabling creation, simulation (DC, AC, transient), and analysis of electronic circuits using PySpice.
    1
    -
  • A
    license
    Not graded
    quality
    D
    maintenance
    Enables MCP-compatible agents to generate Qucs circuit schematics, run simulations, and parse results programmatically.
    2
    MIT