Experiment workflow
Author a plain .cir deck.
Validate (verify_circuit {"path":"ldo.cir","checks":["syntax"]}), run the
sweep in one run_experiments call, read the numbers with analyze_results.
The N cases run as one batch; other sessions can run at the same time.
Values come back parsed, with SI units; if a case produced no result,
completeness reports it and outcome is "partial".
Charts: plot_waveform (interactive, where the client supports it); the
plot recipe is the static fallback.
Loops over many runs, numpy on the samples, or a script you will keep:
from ltspice_mcp.api import Api runs the same six ops in-process and returns
complete results (no paging, no budget); api.reference("<op>") gives an
op's arguments before you guess them. If the server lists a run_code tool,
the same snippet runs there with api already in scope and the engine warm.
Pass a request_id: the same id and args returns the original receipt
instead of re-running (decks are content-addressed, so a later edit does not
change what ran); different args return idempotency_conflict.
Idiom 1 — author .MEAS in the deck
.param ILOAD=1m
.meas tran vout_dc AVG V(out) FROM 4m TO 5m
{"request_id":"ldo-load-1","circuits":[{"path":"ldo.cir"}],
"variations":[{"kind":"assign","assign":{"ILOAD":["1m","10m","100m"]}}],
"analyze":{"recipes":[{"key":"v","metric":"measurements","names":["vout_dc"]}],
"group_by":["ILOAD"]}}
The simulator computes the scalar and the measurements recipe reads it back
from the .log. assign targets must exist in the deck. If you restrict
saves, .save every signal a .meas uses; lint blocks a mismatch.
Idiom 2 — gm/gds/vth/vdsat come from .op (LTspice)
Put .op in the deck; the server adds .options logopinfo to LTspice .op
runs (writing it yourself is harmless).
.op
.options logopinfo
{"sources":[{"label":"bias","job_id":"exp_..."}],
"recipes":[{"key":"m1","metric":"operating_point","device":"m1"}]}
Results are in device_op_points, keyed by the literal @m1[gm] (no m1.gm
shorthand here); device limits the output to one device.
Cap a reply with budget
run_experiments, analyze_results, inspect and jobs take budget, a
response cap in estimated tokens (compact JSON chars/4, minimum 500);
omitted, the response is unchanged. Set one when a call can return a lot
(per_run, long lists). Over the cap the server drops presentation in a fixed
order (echoes, detail opt-ins, smaller pages with valid cursors) and never
facts: failures, observations, warnings and completeness arrive
complete, and a budget_truncated observation says what was cut and how to get
it back.
Other notes
- Open-loop/DC-servo benches and templates: the
spice-bench-craft skill.
analyze_results defaults return the answer (results, coverage,
observations, failures); name detail under include (fields,
per_run, outliers, signals_available). group_by is top-level, never
in a recipe.jobs {"action":"status","request_id":"ldo-load-1"} finds a job whose id you
lost; also wait (timed_out ends the wait, not the job), cancel, list,
runs.skipped cases mean lint blocked that deck — fix it, or
suppress:["save-meas-coverage"]; don't set lint:"warn".inspect reads decks, schematics and libraries, never results:
{"queries":[{"kind":"components","path":"ldo.cir","detail":"full"}]}edit_schematic edits .asc transactionally (expected_sha256 when it
exists); verify_circuit {"path":"amp.asc","reference":"golden.net"} checks
that a schematic matches a netlist.
1---2name: spice-experiments3description: Use for any circuit or SPICE task: ngspice, LTspice, netlists, schematics, amplifiers, filters, regulators, analog or power design. Before running a simulator or writing an analysis script yourself, read this: the sim server runs sweeps and corners in one call and returns parsed numbers (.MEAS scalars, gm/gds/vth, Bode and transient metrics, equivalence checks), no rawfile parsing. SPICE syntax: the ltspice skill.4---56# Experiment workflow78Author a plain `.cir` deck.9Validate (`verify_circuit {"path":"ldo.cir","checks":["syntax"]}`), run the10sweep in one `run_experiments` call, read the numbers with `analyze_results`.1112The N cases run as one batch; other sessions can run at the same time.13Values come back parsed, with SI units; if a case produced no result,14`completeness` reports it and `outcome` is `"partial"`.15Charts: `plot_waveform` (interactive, where the client supports it); the16`plot` recipe is the static fallback.17Loops over many runs, numpy on the samples, or a script you will keep:18`from ltspice_mcp.api import Api` runs the same six ops in-process and returns19complete results (no paging, no budget); `api.reference("<op>")` gives an20op's arguments before you guess them. If the server lists a `run_code` tool,21the same snippet runs there with `api` already in scope and the engine warm.22Pass a `request_id`: the same id and args returns the original receipt23instead of re-running (decks are content-addressed, so a later edit does not24change what ran); different args return `idempotency_conflict`.2526## Idiom 1 — author `.MEAS` in the deck2728```spice29.param ILOAD=1m30.meas tran vout_dc AVG V(out) FROM 4m TO 5m31```32```json33{"request_id":"ldo-load-1","circuits":[{"path":"ldo.cir"}],34 "variations":[{"kind":"assign","assign":{"ILOAD":["1m","10m","100m"]}}],35 "analyze":{"recipes":[{"key":"v","metric":"measurements","names":["vout_dc"]}],36 "group_by":["ILOAD"]}}37```38The simulator computes the scalar and the `measurements` recipe reads it back39from the `.log`. `assign` targets must exist in the deck. If you restrict40saves, `.save` every signal a `.meas` uses; lint blocks a mismatch.4142## Idiom 2 — gm/gds/vth/vdsat come from `.op` (LTspice)4344Put `.op` in the deck; the server adds `.options logopinfo` to LTspice `.op`45runs (writing it yourself is harmless).46```spice47.op48.options logopinfo49```50```json51{"sources":[{"label":"bias","job_id":"exp_..."}],52 "recipes":[{"key":"m1","metric":"operating_point","device":"m1"}]}53```54Results are in `device_op_points`, keyed by the literal `@m1[gm]` (no `m1.gm`55shorthand here); `device` limits the output to one device.5657## Cap a reply with `budget`5859`run_experiments`, `analyze_results`, `inspect` and `jobs` take `budget`, a60response cap in estimated tokens (compact JSON chars/4, minimum 500);61omitted, the response is unchanged. Set one when a call can return a lot62(`per_run`, long lists). Over the cap the server drops presentation in a fixed63order (echoes, detail opt-ins, smaller pages with valid cursors) and never64facts: `failures`, `observations`, `warnings` and `completeness` arrive65complete, and a `budget_truncated` observation says what was cut and how to get66it back.6768## Other notes6970- Open-loop/DC-servo benches and templates: the `spice-bench-craft` skill.71- `analyze_results` defaults return the answer (`results`, `coverage`,72 `observations`, `failures`); name detail under `include` (`fields`,73 `per_run`, `outliers`, `signals_available`). `group_by` is top-level, never74 in a recipe.75- `jobs {"action":"status","request_id":"ldo-load-1"}` finds a job whose id you76 lost; also `wait` (`timed_out` ends the wait, not the job), `cancel`, `list`,77 `runs`.78- `skipped` cases mean `lint` blocked that deck — fix it, or79 `suppress:["save-meas-coverage"]`; don't set `lint:"warn"`.80- `inspect` reads decks, schematics and libraries, never results:81 `{"queries":[{"kind":"components","path":"ldo.cir","detail":"full"}]}`82- `edit_schematic` edits `.asc` transactionally (`expected_sha256` when it83 exists); `verify_circuit {"path":"amp.asc","reference":"golden.net"}` checks84 that a schematic matches a netlist.
cognitohazard