Promptlint MCP

Static linter for AI prompts: contradictions, redundancy, ambiguity, and fluff.

Quick Install

Automated & IDE Setup

Copy the AI prompt to install this server into Claude Code, Cursor, or another agent — or use 1-click editor setup below.

Add to Cursor Add to VS Code

Manual Client & Custom JSON ConfigExpand JSON ▾

Client Config & Setup

Choose your client or environment

Target File:~/Library/Application Support/Claude/claude_desktop_config.json

claude_desktop_config.json

{
  "mcpServers": {
    "promptlint-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "promptlint-mcp"
      ]
    }
  }
}

💡 Paste the JSON block into your client's configuration file under mcpServers, then restart the application.

Documentation Overview

promptlint-mcp

Lint AI prompts like code. Save tokens. Catch contradictions.

A static analyzer for AI prompts — system prompts, agent instructions, tool descriptions — that runs as a CLI and as an MCP server so Claude Code (or any MCP-aware agent) can lint prompts before sending them.

Quick demo

Run promptlint on a typical (silently broken) system prompt:

text

$ node src/cli.mjs examples/bad-prompt.md

promptlint examples/bad-prompt.md
  score  14/100
  tokens 367 → 307 (-60, 16% saved)
  issues 14

  info   [ambiguous-pronoun] Pronoun "that" has no clear referent (line 1)
         → Replace with a concrete noun, e.g. "this" → "the config file".
  ...
  error  [contradiction] Contradicting directives (length): "concise" vs "detailed"
         → Pick one, or scope each with a clear condition (e.g. by task type).
  error  [contradiction] Contradicting directives (commenting): "do not add comments" vs "explain each step"
         → Pick one, or scope each with a clear condition (e.g. by task type).
  info   [trailing-fluff] "please" fluff (match 1 of 1)
         → Delete. AIs do not need politeness tokens.
         · Please
  ...

Two error-level contradictions caught, score clamped to 14/100, 60 tokens (16%) reclaimable via --trim.

And here's --trim in action on a small input:

text

$ echo "You are a helpful assistant. Please always be concise. Thank you for your help! When the user asks a question, handle it carefully." | node src/cli.mjs - --trim

You are a helpful assistant. Always be concise. When the user asks a question, handle it carefully.

See docs/promo/ for posting drafts and the (TODO) asciinema cast.

Why

Contradictions: "be concise" + "be thorough" ships silently and wastes tokens on every request. promptlint flags paired opposites (length / tone / frequency / commenting / asking) as error.
Redundancy: near-duplicate sentences (Jaccard > 0.6) get one warn apiece — delete one.
Ambiguous pronouns: "use it" / "handle that" without a mid-sentence referent is flagged with a line number. Start-of-sentence capitals do NOT count as referents, so normal English doesn't false-positive.
Long code examples: fenced code blocks over ~1200 chars or 30 lines trigger a warn — examples are almost always trimmable to shape-only.
Politeness fluff: Please / Thanks / I hope this helps / Let me know if… / Feel free to… are detected, counted, and (with --trim) stripped while keeping your actual imperatives intact.

Scope: English prompts, prose — not source code. A Japanese prompt or a file of JavaScript will look clean even if it isn't.

Install

Install both the CLI and the MCP server in one go:

Terminal

npm install -g promptlint-mcp

Two binaries are placed on your $PATH:

Bin	What it is
`promptlint`	the CLI (lint a file or stdin)
`promptlint-mcp`	the MCP server (stdio transport)

Run without installing

# CLI: lint a file
npx -p promptlint-mcp promptlint <file>

# CLI: lint stdin
echo "be concise and thorough" | npx -p promptlint-mcp promptlint -

# MCP server (auto-launched by Claude Code via mcp config; see below)
npx -y promptlint-mcp

From source (hacking on it)

git clone https://github.com/sean-sunagaku/promptlint-mcp.git
cd promptlint-mcp
npm install
node src/cli.mjs examples/bad-prompt.md

Requires Node >= 18. Zero runtime deps other than the MCP SDK.

CLI usage

Default human report

node src/cli.mjs examples/bad-prompt.md

Code

promptlint examples/bad-prompt.md
  score  14/100
  tokens 367 → 307 (-60, 16% saved)
  issues 14

  info   [ambiguous-pronoun] Pronoun "that" has no clear referent (line 1)
         → Replace with a concrete noun, e.g. "this" → "the config file".
  ...
  error  [contradiction] Contradicting directives (length): "concise" vs "detailed"
         → Pick one, or scope each with a clear condition (e.g. by task type).
  error  [contradiction] Contradicting directives (commenting): "do not add comments" vs "explain each step"
         → Pick one, or scope each with a clear condition (e.g. by task type).
  info   [trailing-fluff] "thanks" fluff (match 1 of 2)
         → Delete. AIs do not need politeness tokens.
         · Thank you
  info   [trailing-fluff] "please" fluff (match 1 of 1)
         → Delete. AIs do not need politeness tokens.
         · Please
  info   [trailing-fluff] "hope-helps" fluff (match 1 of 1)
         → Delete. AIs do not need politeness tokens.
         · I hope this helps
  ...

A clean prompt (see examples/good-prompt.md) returns score 100/100 with zero issues — silence is a feature.

`--json` for machine consumption

node src/cli.mjs examples/bad-prompt.md --json

config.json

{
  "score": 14,
  "issues": [
    {
      "rule": "ambiguous-pronoun",
      "severity": "info",
      "message": "Pronoun \"that\" has no clear referent (line 1)",
      "line": 1,
      "suggestion": "Replace with a concrete noun, e.g. \"this\" → \"the config file\"."
    },
    {
      "rule": "contradiction",
      "severity": "error",
      "message": "Contradicting directives (length): \"concise\" vs \"detailed\"",
      "suggestion": "Pick one, or scope each with a clear condition (e.g. by task type)."
    }
  ],
  "trimmed": "…",
  "tokensBefore": 367,
  "tokensAfter": 307,
  "saved": 60,
  "savedPercent": 16
}

Empty input adds "note": "empty input". Pure-fluff input (e.g. "Thanks!") that would otherwise trim to empty instead returns the original with "trimmerFallback": true — a safe drop-in never hands a blank prompt to your LLM.

`--trim` to print trimmed output (for piping)

echo "You are a helpful coding assistant. Please always be concise. Thank you for your help! When the user asks a question, handle it carefully. If they provide code, review it. Let me know if anything is unclear. I hope this helps!" \
  | node src/cli.mjs - --trim

Code

You are a helpful coding assistant. Always be concise. When the user asks a question, handle it carefully. If they provide code, review it.

Fenced code blocks are preserved verbatim. Quoted strings ("…") and inline backticks (`…`) are masked before fluff removal so example text survives untouched.

Stdin

cat prompt.md | node src/cli.mjs -

The report header shows promptlint <stdin>.

Other flags

node src/cli.mjs --rules      # list the 5 rule IDs, one per line
node src/cli.mjs --help       # usage

Exit codes

Code	Meaning
0	no errors (warn/info ok)
1	at least one `error`-severity issue
2	bad usage (missing file, read failure, etc.)

MCP server usage

Terminal

claude mcp add promptlint -- npx -y promptlint-mcp

Or add this to ~/.claude.json (user scope) or project .mcp.json (project scope):

config.json

{
  "mcpServers": {
    "promptlint": {
      "command": "npx",
      "args": ["-y", "promptlint-mcp"]
    }
  }
}

If you've globally installed the package, the absolute-path form also works and skips npx's first-run download:

config.json

{
  "mcpServers": {
    "promptlint": {
      "command": "promptlint-mcp"
    }
  }
}

Tools exposed

Tool	Input	Returns
`lint_prompt`	`{ text: string }`	Two `text` content items: `[0]` human one-line summary (`"score: X/100 · issues: N · tokens: A → B …"`), `[1]` full JSON of the `lint()` result (parse with `JSON.parse(result.content[1].text)`).
`trim_prompt`	`{ text: string }`	Two `text` content items: `[0]` the trimmed prompt, `[1]` a savings footer (`"Saved N tokens (P%). Original: A, trimmed: B."`). Does NOT resolve contradictions, redundancy, or ambiguity — run `lint_prompt` for those.

Both tools are pure / idempotent. No network, no filesystem, no state.

Rules

ID	Severity	What it catches	Example trigger
`contradiction`	`error`	Paired opposing directives on length / tone / frequency / prohibition / commenting / asking	`"be concise"` + `"be thorough"`
`redundancy`	`warn`	Two sentences with Jaccard word-set similarity > 0.6	Two paragraphs that both say "respond in English" with different wording
`long-example`	`warn`	Fenced code block > 1200 chars or > 30 lines	A 40-line helper function pasted inline
`ambiguous-pronoun`	`info`	`it` / `this` / `that` / `these` / `those` with no mid-sentence concrete referent	`"Use it to figure out what to do."`
`trailing-fluff`	`info`	Politeness / filler: `please`, `thanks`, `I hope this helps`, `let me know if…`, `feel free to…`, `sorry`, `certainly/absolutely/of course`	`"Please refactor the code. Thanks!"`

Read the full README →View source on GitHub →

Related MCP Servers

View all in Developer Tools View all alternatives

Reviews

No reviews yet — be the first to share how this listing worked for you.

Frequently Asked Questions about Promptlint MCP

Add the following block to your claude_desktop_config.json under mcpServers: "mcpServers": { "promptlint-mcp": { "command": "npx", "args": ["-y", "Promptlint MCP"] } }

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Technical Specs & Signals

CategoryDeveloper Tools

27Quality signal: Emerging · 27/100How this signal is calculated ▾

Server availabilityNot measured

Not scored for repo-hosted servers — we can't reach the running server, only its GitHub page. Hosted MCP endpoints are health-checked live.

Verified ownership8/20

Documentation & tools11/30

Adoption & activity1/15

Community engagement0/10

A guidance signal from public completeness & health data — not a user rating. New listings start lower and rise as they add docs, get verified, and grow adoption. Signals we can't observe for a listing are skipped, not counted against it.

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More in 💻 Developer Tools →Best MCP servers for Developers →Alternatives to Promptlint MCP →Install in Claude Desktop Install in Cursor Install in VS Code

Promptlint MCP

Static linter for AI prompts: contradictions, redundancy, ambiguity, and fluff.

Quick Install

Automated & IDE Setup

Copy the AI prompt to install this server into Claude Code, Cursor, or another agent — or use 1-click editor setup below.

Add to Cursor Add to VS Code

Manual Client & Custom JSON ConfigExpand JSON ▾

Client Config & Setup

Choose your client or environment

Target File:~/Library/Application Support/Claude/claude_desktop_config.json

claude_desktop_config.json

{
  "mcpServers": {
    "promptlint-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "promptlint-mcp"
      ]
    }
  }
}

💡 Paste the JSON block into your client's configuration file under mcpServers, then restart the application.

Documentation Overview

promptlint-mcp

Lint AI prompts like code. Save tokens. Catch contradictions.

Quick demo

Run promptlint on a typical (silently broken) system prompt:

text

$ node src/cli.mjs examples/bad-prompt.md

promptlint examples/bad-prompt.md
  score  14/100
  tokens 367 → 307 (-60, 16% saved)
  issues 14

  info   [ambiguous-pronoun] Pronoun "that" has no clear referent (line 1)
         → Replace with a concrete noun, e.g. "this" → "the config file".
  ...
  error  [contradiction] Contradicting directives (length): "concise" vs "detailed"
         → Pick one, or scope each with a clear condition (e.g. by task type).
  error  [contradiction] Contradicting directives (commenting): "do not add comments" vs "explain each step"
         → Pick one, or scope each with a clear condition (e.g. by task type).
  info   [trailing-fluff] "please" fluff (match 1 of 1)
         → Delete. AIs do not need politeness tokens.
         · Please
  ...

Two error-level contradictions caught, score clamped to 14/100, 60 tokens (16%) reclaimable via --trim.

And here's --trim in action on a small input:

text

$ echo "You are a helpful assistant. Please always be concise. Thank you for your help! When the user asks a question, handle it carefully." | node src/cli.mjs - --trim

You are a helpful assistant. Always be concise. When the user asks a question, handle it carefully.

See docs/promo/ for posting drafts and the (TODO) asciinema cast.

Why

Contradictions: "be concise" + "be thorough" ships silently and wastes tokens on every request. promptlint flags paired opposites (length / tone / frequency / commenting / asking) as error.
Redundancy: near-duplicate sentences (Jaccard > 0.6) get one warn apiece — delete one.
Ambiguous pronouns: "use it" / "handle that" without a mid-sentence referent is flagged with a line number. Start-of-sentence capitals do NOT count as referents, so normal English doesn't false-positive.
Long code examples: fenced code blocks over ~1200 chars or 30 lines trigger a warn — examples are almost always trimmable to shape-only.
Politeness fluff: Please / Thanks / I hope this helps / Let me know if… / Feel free to… are detected, counted, and (with --trim) stripped while keeping your actual imperatives intact.

Scope: English prompts, prose — not source code. A Japanese prompt or a file of JavaScript will look clean even if it isn't.

Install

Install both the CLI and the MCP server in one go:

Terminal

npm install -g promptlint-mcp

Two binaries are placed on your $PATH:

Bin	What it is
`promptlint`	the CLI (lint a file or stdin)
`promptlint-mcp`	the MCP server (stdio transport)

Run without installing

# CLI: lint a file
npx -p promptlint-mcp promptlint <file>

# CLI: lint stdin
echo "be concise and thorough" | npx -p promptlint-mcp promptlint -

# MCP server (auto-launched by Claude Code via mcp config; see below)
npx -y promptlint-mcp

From source (hacking on it)

git clone https://github.com/sean-sunagaku/promptlint-mcp.git
cd promptlint-mcp
npm install
node src/cli.mjs examples/bad-prompt.md

Requires Node >= 18. Zero runtime deps other than the MCP SDK.

CLI usage

Default human report

node src/cli.mjs examples/bad-prompt.md

Code

promptlint examples/bad-prompt.md
  score  14/100
  tokens 367 → 307 (-60, 16% saved)
  issues 14

  info   [ambiguous-pronoun] Pronoun "that" has no clear referent (line 1)
         → Replace with a concrete noun, e.g. "this" → "the config file".
  ...
  error  [contradiction] Contradicting directives (length): "concise" vs "detailed"
         → Pick one, or scope each with a clear condition (e.g. by task type).
  error  [contradiction] Contradicting directives (commenting): "do not add comments" vs "explain each step"
         → Pick one, or scope each with a clear condition (e.g. by task type).
  info   [trailing-fluff] "thanks" fluff (match 1 of 2)
         → Delete. AIs do not need politeness tokens.
         · Thank you
  info   [trailing-fluff] "please" fluff (match 1 of 1)
         → Delete. AIs do not need politeness tokens.
         · Please
  info   [trailing-fluff] "hope-helps" fluff (match 1 of 1)
         → Delete. AIs do not need politeness tokens.
         · I hope this helps
  ...

A clean prompt (see examples/good-prompt.md) returns score 100/100 with zero issues — silence is a feature.

`--json` for machine consumption

node src/cli.mjs examples/bad-prompt.md --json

config.json

{
  "score": 14,
  "issues": [
    {
      "rule": "ambiguous-pronoun",
      "severity": "info",
      "message": "Pronoun \"that\" has no clear referent (line 1)",
      "line": 1,
      "suggestion": "Replace with a concrete noun, e.g. \"this\" → \"the config file\"."
    },
    {
      "rule": "contradiction",
      "severity": "error",
      "message": "Contradicting directives (length): \"concise\" vs \"detailed\"",
      "suggestion": "Pick one, or scope each with a clear condition (e.g. by task type)."
    }
  ],
  "trimmed": "…",
  "tokensBefore": 367,
  "tokensAfter": 307,
  "saved": 60,
  "savedPercent": 16
}

`--trim` to print trimmed output (for piping)

echo "You are a helpful coding assistant. Please always be concise. Thank you for your help! When the user asks a question, handle it carefully. If they provide code, review it. Let me know if anything is unclear. I hope this helps!" \
  | node src/cli.mjs - --trim

Code

You are a helpful coding assistant. Always be concise. When the user asks a question, handle it carefully. If they provide code, review it.

Fenced code blocks are preserved verbatim. Quoted strings ("…") and inline backticks (`…`) are masked before fluff removal so example text survives untouched.

Stdin

cat prompt.md | node src/cli.mjs -

The report header shows promptlint <stdin>.

Other flags

node src/cli.mjs --rules      # list the 5 rule IDs, one per line
node src/cli.mjs --help       # usage

Exit codes

Code	Meaning
0	no errors (warn/info ok)
1	at least one `error`-severity issue
2	bad usage (missing file, read failure, etc.)

MCP server usage

Terminal

claude mcp add promptlint -- npx -y promptlint-mcp

Or add this to ~/.claude.json (user scope) or project .mcp.json (project scope):

config.json

{
  "mcpServers": {
    "promptlint": {
      "command": "npx",
      "args": ["-y", "promptlint-mcp"]
    }
  }
}

If you've globally installed the package, the absolute-path form also works and skips npx's first-run download:

config.json

{
  "mcpServers": {
    "promptlint": {
      "command": "promptlint-mcp"
    }
  }
}

Tools exposed

Tool	Input	Returns
`lint_prompt`	`{ text: string }`	Two `text` content items: `[0]` human one-line summary (`"score: X/100 · issues: N · tokens: A → B …"`), `[1]` full JSON of the `lint()` result (parse with `JSON.parse(result.content[1].text)`).
`trim_prompt`	`{ text: string }`	Two `text` content items: `[0]` the trimmed prompt, `[1]` a savings footer (`"Saved N tokens (P%). Original: A, trimmed: B."`). Does NOT resolve contradictions, redundancy, or ambiguity — run `lint_prompt` for those.

Both tools are pure / idempotent. No network, no filesystem, no state.

Rules

ID	Severity	What it catches	Example trigger
`contradiction`	`error`	Paired opposing directives on length / tone / frequency / prohibition / commenting / asking	`"be concise"` + `"be thorough"`
`redundancy`	`warn`	Two sentences with Jaccard word-set similarity > 0.6	Two paragraphs that both say "respond in English" with different wording
`long-example`	`warn`	Fenced code block > 1200 chars or > 30 lines	A 40-line helper function pasted inline
`ambiguous-pronoun`	`info`	`it` / `this` / `that` / `these` / `those` with no mid-sentence concrete referent	`"Use it to figure out what to do."`
`trailing-fluff`	`info`	Politeness / filler: `please`, `thanks`, `I hope this helps`, `let me know if…`, `feel free to…`, `sorry`, `certainly/absolutely/of course`	`"Please refactor the code. Thanks!"`

Read the full README →View source on GitHub →

Related MCP Servers

View all in Developer Tools View all alternatives

Reviews

No reviews yet — be the first to share how this listing worked for you.

Frequently Asked Questions about Promptlint MCP

Add the following block to your claude_desktop_config.json under mcpServers: "mcpServers": { "promptlint-mcp": { "command": "npx", "args": ["-y", "Promptlint MCP"] } }

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Technical Specs & Signals

CategoryDeveloper Tools

27Quality signal: Emerging · 27/100How this signal is calculated ▾

Server availabilityNot measured

Not scored for repo-hosted servers — we can't reach the running server, only its GitHub page. Hosted MCP endpoints are health-checked live.

Verified ownership8/20

Documentation & tools11/30

Adoption & activity1/15

Community engagement0/10

★ Spotlight Slot

Feature Your MCP Server

Get maximum visibility for your server across our directory, search results, and detail pages.

Spotlight Your Server

Own this project?

Free dofollow backlink: add your website and place the AllMCPs badge on it — no claim needed. We detect it automatically and keep it verified as long as the badge stays live.

Claim & get free dofollow

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Explore more

More in 💻 Developer Tools →Best MCP servers for Developers →Alternatives to Promptlint MCP →Install in Claude Desktop Install in Cursor Install in VS Code

Promptlint MCP

Quick Install

Client Config & Setup

Documentation Overview

promptlint-mcp

Quick demo

Why

Install

Run without installing

From source (hacking on it)

CLI usage

Default human report

--json for machine consumption

--trim to print trimmed output (for piping)

Stdin

Other flags

Exit codes

MCP server usage

Tools exposed

Rules

Related MCP Servers

Reviews

Frequently Asked Questions about Promptlint MCP

AllMCPs Directory Badge

Technical Specs & Signals

Feature Your MCP Server

Own this project?

Share & Embed

Explore more

Promptlint MCP

Quick Install

Client Config & Setup

Documentation Overview

promptlint-mcp

Quick demo

Why

Install

Run without installing

From source (hacking on it)

CLI usage

Default human report

--json for machine consumption

--trim to print trimmed output (for piping)

Stdin

Other flags

Exit codes

MCP server usage

Tools exposed

Rules

Related MCP Servers

Reviews

Frequently Asked Questions about Promptlint MCP

AllMCPs Directory Badge

Technical Specs & Signals

Feature Your MCP Server

Own this project?

Share & Embed

Explore more

`--json` for machine consumption

`--trim` to print trimmed output (for piping)

`--json` for machine consumption

`--trim` to print trimmed output (for piping)