DIAGNOSTICS FOR YOUR CODING AGENT v1.2.1Schema 1.4

Less noise.More signal.

A clearer feedback loop
for the work ahead.

A local MCP server that turns your JS/TS diagnostics into grouped, prioritized context. Keep your toolchain. Give your agent the signal.

Get started Read the docs

Benchmark illustration: 52 diagnostics become two rule-based clusters, with 21 type errors and 31 unused-variable diagnostics. No automatic fixes. — Illustrated benchmark · not a live scan

ONE REPEATED-RULE FIXTURE / 11 FILES

52diagnostics2rule-based clusters

Two groups to investigate.
Not fifty-two separate distractions.

P1Type mismatchTS232221

P5Unused variablesno-unused-vars31

Inspect the result

Illustrated benchmark. Not a live scan or a root-cause verdict.

npm install --save-dev signalint-mcp@1.2.1

LOCAL STDIOOPEN SOURCE / MITNODE ≥ 22.12

YOUR CLIENT.
YOUR WORKFLOW.Setup guides

Claude Code Cursor Codex CLI Antigravity Visual Studio Code Windsurf Zed

01 / THE RESULT

Read the pattern.
Keep the detail.

A smaller thing to read. A concrete place to start. Inspect the example, then switch to the raw excerpt.

›check_projectMCP TOOL

Less to read. More to act on.

1.4

P1Type mismatchTS2322·21 issues across 11 files

src/file01.ts:3:14

Type 'string' is not assignable to type 'number'.

Investigate whether these TS2322 occurrences share a cause.

P5Unused variablesno-unused-vars·31 issues across 11 files

Inspect the repeated no-unused-vars diagnostics.

Use get_issue_detail for matching normalized diagnostics.

TypeScript Oxlintranked · no auto-fix

›tsc --pretty falseEXCERPT

src/file01.ts:3:14error TS2322

Type 'string' is not assignable to type 'number'.

src/file02.ts:3:14error TS2322

Type 'string' is not assignable to type 'number'.

src/file03.ts:3:14error TS2322

Type 'string' is not assignable to type 'number'.

src/file04.ts:3:14error TS2322

Type 'string' is not assignable to type 'number'.

... repeated diagnostics across 11 files

A CHECK, ORGANIZED

Context.
Not a compiler dump.

Group repeated rules. Put higher-priority issues first. Request matching diagnostics when you need to investigate.

01Grouped by rule & scope
02Ranked P1 → P5
03Normalized detail on demand

The response contract

Counts are bounded, not every response’s byte size. Read the limits.

OBSERVED / NOT PROMISED

965B

One grouped response.
Pretty JSON, measured in bytes.

Read the measurement

Compare with

86.9% fewer bytes in this fixture.

Terminal output7,370 B

Grouped response965 B

Audit rerun, not a universal guarantee. 52 issues · 11 files · 2 clusters. Pretty JSON bytes ≠ MCP wire traffic or model tokens; paths and serialization affect size.

02 / AFTER THE EDIT

A check is a baseline.
Not the end.

Save the context. Make the edit. Compare what changed, then check what was actually covered.

BASELINE → EDIT → VERIFYSnapshots & edit verification

01
Keep the baselinecheck_project
Save the check ID, scope and engine outcomes.
02
Verify your editafter_edit_check
Check changed files against an optional baseline.
03
Read the deltacompare_diagnostics
Introduced. Resolved. Unchanged. Confirm coverage.

A delta is a diagnostic comparison—not proof of a correct repair.

13 MCP TOOLS / AUDITED 1.2.1

A little further
into the workflow.

Use the parts you need.
Read the boundaries first.

All 13 tools

After-edit hooks

Host-shaped feedback. Preview the configuration; review the policy limits.

HOST ADAPTERS 02

Workspace planning

Opt-in pnpm discovery, dependency ordering and partitioned TypeScript state.

OPT-IN 03

Supplied live diagnostics

Normalize supplied LSP or external language reports. No built-in watcher.

CALLER-SUPPLIED 04

Explicit patch transactions

Stage replacement content, then apply. Adjacent replacements; in-process best-effort rollback.

SOURCE-WRITING

03 / A BRIDGE. NOT ANOTHER LINTER.

Your toolchain.
Still your toolchain.

Signalint runs in your project environment. Your agent may use remote models. The boundary matters.

IN YOUR PROJECTNO SIGNALINT CLOUD API

YOUR TOOLCHAINSTATIC CHECK MODEL / NOT LIVE CONNECTIONS

Your toolchain

Use the engines your project configures.

OxlintJavaScript / TypeScript lint

TypeScriptConfigured compiler program

BiomeProject-configured checks

ESLintProject-configured checks

Signalint

Normalize.
Group & prioritize.
Retain & compare.

stdio MCP

Your coding agent

Claude CodeClient setup guide

CursorClient setup guide

Codex CLIClient setup guide

All seven setup guides

A bridge from your diagnostic engines to your MCP client. Diagnostic checks do not edit source; explicit apply is a separate operation. Client marks are setup-guide examples, not active connections or compatibility certification. Your client controls whether feedback is sent to a remote model.

No Signalint cloud APIExplicit apply onlyNo Signalint API key

Explore the architecture

04 / IN THE LOOP

Built for the
next check.

Not just a smaller first response. A more useful way to return to the work.

Auto switches every 8 seconds.
Interact to pause; press play to resume.
Use ↑ / ↓ to explore.

CAPABILITY / LAYER STUDY

SELECT A LAYER

The pattern comes first.

Repeated diagnostics become rule-based clusters. Systemic errors come before lower-priority warnings; matching normalized details are available when you need them.

Clustering & priorities

A rule-and-scope heuristic, not a proven root cause.

A match, not a shortcut.

Reuse results when the engine’s cache key matches. File checks filter displayed paths; TypeScript still checks its configured program and uses a bounded source-metadata fingerprint.

Cache behavior & limits

Content, compiler inputs and scope have documented edges.

This grouping specimen is static without JavaScript. Read the cache guide or session-history guide for the other behaviors.

05 / START IN YOUR PROJECT

A small setup.
A useful next step.

Bring your engines. Connect your client. Make your first check count.

PROJECT-LOCAL / NO SIGNALINT API KEY

01
Add Signalint
A dev dependency alongside the diagnostic engines you choose.
02
Initialize your project
Detect engine configuration and select your MCP client.
03
Inspect the environment
Doctor reports a limited set of setup checks.

Follow the quickstart Find your client’s setup guide

Engines are optional peers, not bundled promises. Install the ones your project needs.

~ / your-projectSETUP

# Install in your project

$npm install --save-dev signalint-mcp@1.2.1

# Configure engines and your MCP client

$npx signalint-mcp init

# Verify your environment

$npx --no-install signalint doctor

# Install in your project

$pnpm add -D signalint-mcp@1.2.1

# Configure engines and your MCP client

$pnpm exec signalint init

# Verify your environment

$pnpm exec signalint doctor

# Install in your project

$yarn add -D signalint-mcp@1.2.1

# Configure engines and your MCP client

$yarn run signalint init

# Verify your environment

$yarn run signalint doctor

Bring your project's engines: Oxlint, TypeScript, Biome, or ESLint. Signalint no longer bundles Oxlint/TypeScript. Engine setup

FROM THE PROJECT

Current package. Verified guidance.

Release notes

Latest on npm: v1.2.1
Package requires Node: >=22.12.0
Project last updated: Oct 11, 2026
Docs verified against: v1.2.1

Saved project snapshot. Live metadata refreshes when available.

Less noise.More signal.

Read the pattern.
Keep the detail.

Less to read. More to act on.

Context.
Not a compiler dump.

86.9% fewer bytes in this fixture.

94.9% fewer bytes in this fixture.

A check is a baseline.
Not the end.

A little further
into the workflow.

After-edit hooks

Workspace planning

Supplied live diagnostics

Explicit patch transactions

Your toolchain.
Still your toolchain.

Your toolchain

Signalint

Your coding agent

Built for the
next check.

The pattern comes first.

A match, not a shortcut.

Some errors come back.

A small setup.
A useful next step.

Current package. Verified guidance.

Less noise.More signal.

Read the pattern.Keep the detail.

Less to read. More to act on.

Context.Not a compiler dump.

86.9% fewer bytes in this fixture.

94.9% fewer bytes in this fixture.

A check is a baseline.Not the end.

A little furtherinto the workflow.

After-edit hooks

Workspace planning

Supplied live diagnostics

Explicit patch transactions

Your toolchain.Still your toolchain.

Your toolchain

Signalint

Your coding agent

Built for thenext check.

The pattern comes first.

A match, not a shortcut.

Some errors come back.

A small setup.A useful next step.

Current package. Verified guidance.

Read the pattern.
Keep the detail.

Context.
Not a compiler dump.

A check is a baseline.
Not the end.

A little further
into the workflow.

Your toolchain.
Still your toolchain.

Built for the
next check.

A small setup.
A useful next step.