useSignal
QR codes, JSON diff/format, hashes, JWT, cron, timestamps, placeholders, flowcharts, forms, regex.
Should I use this
Quality & Safety
Findings (3)
- HIGHTool poisoning patterns detected
- MEDIUMTool 'usesignal_placeholder_image' description contains placeholder textin usesignal_placeholder_image
- INFOTool description contains placeholder or incomplete textin usesignal_placeholder_image
Based on automated analysis of tool definitions and protocol compliance.
Context Cost
This is the approximate number of tokens consumed each time the server's tools are loaded into a model's context. Higher counts reduce the attention available for other tasks.
Install
One-Click Install
Add this to your `claude_desktop_config.json` file:
{
"mcpServers": {
"usesignal": {
"url": "https://www.usesignal.dev/mcp"
}
}
}Remote endpoints
https://www.usesignal.dev/mcpstreamable-httpWhat it can do
Tool inventory
Tools (12)
🟢usesignal_generate_form(json, title, overrides)
Generate an editable form from a JSON object. Returns nested field paths, JSON Schema, HTML, React JSX and config exports. Arrays and nulls use JSON textareas. Values are processed in memory; avoid secrets. To show an interactive preview, call usesignal_open_workbench with this result input.
Input Schema
{
"type": "object",
"properties": {
"json": {
"type": "string",
"maxLength": 50000
},
"title": {
"type": "string",
"maxLength": 120,
"default": "Generated form"
},
"overrides": {
"type": "array",
"items": {
"type": "object",
"properties": {
"path": {
"type": "array",
"items": {
"type": "string"
},
"maxItems": 9
},
"label": {
"type": "string",
"maxLength": 120
},
"type": {
"type": "string",
"enum": [
"text",
"email",
"number",
"checkbox",
"textarea"
]
},
"required": {
"type": "boolean"
}
},
"required": [
"path"
],
"additionalProperties": false
},
"maxItems": 100,
"default": []
}
},
"required": [
"json"
],
"additionalProperties": false,
"$schema": "http://json-schema.org/draft-07/schema#"
}🟢usesignal_generate_colors(baseColor)
Generate light and dark semantic color tokens from a six-digit hex brand color. Returns a shade scale, measured text contrast checks and CSS, JSON and Tailwind exports. This measures listed color pairs only, not whole-page accessibility. Call usesignal_open_workbench with the result input to preview.
Input Schema
{
"type": "object",
"properties": {
"baseColor": {
"type": "string",
"pattern": "^#[0-9a-fA-F]{6}$"
}
},
"required": [
"baseColor"
],
"additionalProperties": false,
"$schema": "http://json-schema.org/draft-07/schema#"
}🟢usesignal_test_regex(pattern, flags, text, tests)
Execute a JavaScript regular expression against text and expected match/non-match test cases. Returns indexed matches and capture groups. Flags use JavaScript semantics. Execution times out after 500ms. Call usesignal_open_workbench with result input to highlight matches.
Input Schema
{
"type": "object",
"properties": {
"pattern": {
"type": "string",
"maxLength": 1000
},
"flags": {
"type": "string",
"maxLength": 8,
"default": "g"
},
"text": {
"type": "string",
"maxLength": 20000
},
"tests": {
"type": "array",
"items": {
"type": "object",
"properties": {
"text": {
"type": "string",
"maxLength": 2000
},
"shouldMatch": {
"type": "boolean"
}
},
"required": [
"text",
"shouldMatch"
],
"additionalProperties": false
},
"maxItems": 50,
"default": []
}
},
"required": [
"pattern",
"text"
],
"additionalProperties": false,
"$schema": "http://json-schema.org/draft-07/schema#"
}🟢usesignal_generate_qr(type, values, dark, light, moduleStyle, ...)
Generate a scannable QR code for a link, text, Wi-Fi network, contact card (vCard), email, SMS, phone number, WhatsApp chat or UPI payment. Returns the encoded payload, an SVG file and a PNG preview image. values by type: url{url}; text{text}; wifi{ssid,password,security:WPA|WEP|nopass,hidden}; vcard{firstName,lastName,phone,email,org,title,website,address}; email{to,subject,body}; sms{phone,message}; phone{phone}; whatsapp{phone,message}; upi{vpa,name,amount,note}.
Input Schema
{
"type": "object",
"properties": {
"type": {
"type": "string",
"enum": [
"url",
"text",
"wifi",
"upi",
"vcard",
"whatsapp",
"email",
"sms",
"phone"
]
},
"values": {
"type": "object",
"additionalProperties": {
"anyOf": [
{
"type": "string",
"maxLength": 2000
},
{
"type": "boolean"
},
{
"type": "number"
}
]
}
},
"dark": {
"type": "string",
"pattern": "^#[0-9a-fA-F]{6}$",
"default": "#111111"
},
"light": {
"$ref": "#/properties/dark",
"default": "#FFFFFF"
},
"moduleStyle": {
"type": "string",
"enum": [
"square",
"rounded",
"dots"
],
"default": "square"
},
"errorCorrection": {
"type": "string",
"enum": [
"L",
"M",
"Q",
"H"
],
"default": "M"
},
"margin": {
"type": "integer",
"minimum": 0,
"maximum": 16,
"default": 4
}
},
"required": [
"type",
"values"
],
"additionalProperties": false,
"$schema": "http://json-schema.org/draft-07/schema#"
}🟢usesignal_encode_decode(operation, text)
Exact text transforms: Base64 encode/decode (UTF-8), URL encode/decode, decode a JWT header and payload with readable exp/iat/nbf dates (the signature is not verified), or hash text with MD5, SHA-1, SHA-256 and SHA-512. Use this instead of computing hashes or Base64 by hand.
Input Schema
{
"type": "object",
"properties": {
"operation": {
"type": "string",
"enum": [
"base64_encode",
"base64_decode",
"url_encode",
"url_decode",
"jwt_decode",
"hash"
]
},
"text": {
"type": "string",
"maxLength": 100000
}
},
"required": [
"operation",
"text"
],
"additionalProperties": false,
"$schema": "http://json-schema.org/draft-07/schema#"
}🟢usesignal_explain_cron(expression, timeZone, count)
Explain a standard 5-field cron expression (minute hour day-of-month month day-of-week) in plain English and list its next run times in a given time zone, handling daylight saving time.
Input Schema
{
"type": "object",
"properties": {
"expression": {
"type": "string",
"maxLength": 200
},
"timeZone": {
"type": "string",
"maxLength": 64,
"default": "UTC",
"description": "IANA time zone, e.g. Asia/Kolkata or America/New_York"
},
"count": {
"type": "integer",
"minimum": 1,
"maximum": 20,
"default": 5
}
},
"required": [
"expression"
],
"additionalProperties": false,
"$schema": "http://json-schema.org/draft-07/schema#"
}🟢usesignal_convert_timestamp(value, timeZone)
Convert a Unix timestamp (seconds or milliseconds) or an ISO 8601 date into ISO, UTC, epoch seconds/milliseconds, a relative time and the local time in a given time zone.
Input Schema
{
"type": "object",
"properties": {
"value": {
"type": "string",
"maxLength": 100
},
"timeZone": {
"type": "string",
"maxLength": 64,
"default": "UTC",
"description": "IANA time zone, e.g. Asia/Kolkata or America/New_York"
}
},
"required": [
"value"
],
"additionalProperties": false,
"$schema": "http://json-schema.org/draft-07/schema#"
}🟢usesignal_diff_json(left, right, arrays)
Compare two JSON documents structurally and list every added, removed and changed value with its JSONPath. Numbers compare exactly. Arrays match by content by default, so an inserted item shows as one addition; use arrays:"position" to compare index by index.
Input Schema
{
"type": "object",
"properties": {
"left": {
"type": "string",
"maxLength": 200000
},
"right": {
"type": "string",
"maxLength": 200000
},
"arrays": {
"type": "string",
"enum": [
"content",
"position"
],
"default": "content"
}
},
"required": [
"left",
"right"
],
"additionalProperties": false,
"$schema": "http://json-schema.org/draft-07/schema#"
}🟢usesignal_format_json(json, mode, indent, sortKeys, repair)
Validate, pretty-print or minify JSON, optionally sorting keys. Invalid JSON reports the exact line and column; with repair (default on) it fixes common problems such as trailing commas, single quotes, comments and unquoted keys, and lists each fix.
Input Schema
{
"type": "object",
"properties": {
"json": {
"type": "string",
"maxLength": 200000
},
"mode": {
"type": "string",
"enum": [
"format",
"minify"
],
"default": "format"
},
"indent": {
"type": "string",
"enum": [
"2",
"4",
"tab"
],
"default": "2"
},
"sortKeys": {
"type": "boolean",
"default": false
},
"repair": {
"type": "boolean",
"default": true
}
},
"required": [
"json"
],
"additionalProperties": false,
"$schema": "http://json-schema.org/draft-07/schema#"
}🟢usesignal_placeholder_image(width, height, text, background, color, ...)
Create a placeholder image URL (served by usesignal.dev) plus HTML, Markdown and CSS snippets, for mockups, prototypes, seed data and layouts. Width and height up to 4000 px.
Input Schema
{
"type": "object",
"properties": {
"width": {
"type": "integer",
"minimum": 1,
"maximum": 4000
},
"height": {
"type": "integer",
"minimum": 1,
"maximum": 4000
},
"text": {
"type": "string",
"maxLength": 120
},
"background": {
"type": "string",
"pattern": "^#[0-9a-fA-F]{6}$"
},
"color": {
"$ref": "#/properties/background"
},
"style": {
"type": "string",
"enum": [
"minimal",
"grid",
"gradient",
"dark",
"glass"
],
"default": "minimal"
},
"pattern": {
"type": "string",
"enum": [
"plain",
"grid",
"diagonal",
"dots",
"minimal"
]
},
"radius": {
"type": "integer",
"minimum": 0,
"maximum": 999
}
},
"required": [
"width",
"height"
],
"additionalProperties": false,
"$schema": "http://json-schema.org/draft-07/schema#"
}🟢usesignal_flowchart(mode, input, direction)
Turn JavaScript/TypeScript code, arrow steps or Mermaid-style arrows into a flowchart, returned as Mermaid source and an SVG diagram. Steps mode uses one flow per line: "Start -> Validate -> Save" and branches like "Validate -- No --> Show error".
Input Schema
{
"type": "object",
"properties": {
"mode": {
"type": "string",
"enum": [
"code",
"steps",
"mermaid"
]
},
"input": {
"type": "string",
"maxLength": 20000
},
"direction": {
"type": "string",
"enum": [
"vertical",
"horizontal"
],
"default": "vertical"
}
},
"required": [
"mode",
"input"
],
"additionalProperties": false,
"$schema": "http://json-schema.org/draft-07/schema#"
}🟢usesignal_open_workbench(tool, input)
Show the editable useSignal UI. First call a useSignal data tool, then pass its returned input and matching tool name. Recomputes from validated inputs; no shared state.
Input Schema
{
"type": "object",
"properties": {
"tool": {
"type": "string",
"enum": [
"usesignal_generate_form",
"usesignal_generate_colors",
"usesignal_test_regex",
"usesignal_generate_qr",
"usesignal_encode_decode",
"usesignal_explain_cron",
"usesignal_convert_timestamp",
"usesignal_diff_json",
"usesignal_format_json",
"usesignal_placeholder_image",
"usesignal_flowchart"
]
},
"input": {
"type": "object",
"additionalProperties": {}
}
},
"required": [
"tool",
"input"
],
"additionalProperties": false,
"$schema": "http://json-schema.org/draft-07/schema#"
}Community
Evidence