toolkit-mcp-server

by cyanheads

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TypeScript

toolkit-mcp-server: generate QR code

toolkit_generate_qr

Read-onlyIdempotent

Generate QR codes from text or URLs, choosing SVG, PNG, or terminal output with adjustable error correction and sizing.

Instructions

Encode text or a URL into a QR code. data is the content to encode (a link, a generated identifier such as toolkit_generate_id's ids[0], or any string). format selects the output: svg returns inline SVG markup sized in pixels, png_base64 returns base64-encoded PNG bytes (with mimeType and byteLength), and terminal returns plain Unicode half-block characters (no escape codes) for a monospace display, drawn for a dark background: light modules, quiet zone included, are blocks and dark modules are spaces. errorCorrection (L/M/Q/H) trades data capacity for damage tolerance, margin sets the quiet-zone width in modules, and scale sets pixels per module for svg and png_base64, so both are (modules + 2 × margin) × scale pixels per side. The returned version (1–40) reflects how dense the encoded data is. png_base64 rejects an image past 2048 px per side with a typed raster_too_large error, so a dense symbol needs a lower scale; svg is vector markup and carries no such limit.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`data`	Yes	The text or URL to encode, stored as UTF-8. Capacity is counted in bytes: 2953 UTF-8 bytes is the absolute ceiling (QR version 40, level L, byte mode). The 2953-character limit here is only an upper bound, since a non-ASCII character takes 2–4 bytes. Usable capacity drops at higher errorCorrection levels, so over-capacity data is rejected with a typed data_too_large error rather than a generic failure.
`scale`	No	Pixels per module for svg (its width and height) and png_base64. Ignored for terminal. png_base64 also bounds the whole image at 2048 px per side, so a dense symbol or a wide margin admits a lower scale than 32 there.
`format`	No	Output format: svg markup, png_base64 (raster bytes), or terminal (plain Unicode half-blocks, drawn for a dark background).	svg
`margin`	No	Quiet-zone width in modules around the symbol. The spec recommends 4.
`errorCorrection`	No	Error-correction level: L (~7% recoverable) to H (~30%). Higher tolerance lowers data capacity.	M

Output Schema

TableJSON Schema

Name	Required	Description
`error`	No	Present when the call failed. Absent on success.
`format`	No	The format that was produced.
`content`	No	The QR artifact: SVG markup, the terminal half-block grid (newline-separated rows), or base64 PNG bytes for png_base64.
`version`	No	QR symbol version (1–40); higher versions hold denser data and indicate denser content.
`mimeType`	No	MIME type of content for image formats. Absent for the terminal format.
`byteLength`	No	Decoded byte size of the PNG. Present only for png_base64.

Schema Changelog

Changes observed during successful MCP inspections.

Changed4 schema fields changedv2.3.1Sep 25, 2026

changedInput schema / properties / data / description

Previous value: -"The text or URL to encode. 2953 is the absolute ceiling (QR version 40, level L, byte mode); usable capacity drops at higher errorCorrection levels, so over-capacity data is rejected with a typed data_too_large error rather than a generic failure."New value: +"The text or URL to encode, stored as UTF-8. Capacity is counted in bytes: 2953 UTF-8 bytes is the absolute ceiling (QR version 40, level L, byte mode). The 2953-character limit here is only an upper bound, since a non-ASCII character takes 2–4 bytes. Usable capacity drops at higher errorCorrection levels, so over-capacity data is rejected with a typed data_too_large error rather than a generic failure."

changedInput schema / properties / format / description

Previous value: -"Output format: svg markup, png_base64 (raster bytes), or a terminal-renderable string."New value: +"Output format: svg markup, png_base64 (raster bytes), or terminal (plain Unicode half-blocks, drawn for a dark background)."

changedInput schema / properties / scale / description

Previous value: -"Pixels per module for raster (png_base64) output. Ignored for terminal. png_base64 also bounds the whole image at 2048 px per side, so a dense symbol or a wide margin admits a lower scale than 32."New value: +"Pixels per module for svg (its width and height) and png_base64. Ignored for terminal. png_base64 also bounds the whole image at 2048 px per side, so a dense symbol or a wide margin admits a lower scale than 32 there."

changedOutput schema / properties / content / description

Previous value: -"The QR artifact: SVG markup, a terminal-renderable string, or base64 PNG bytes for png_base64."New value: +"The QR artifact: SVG markup, the terminal half-block grid (newline-separated rows), or base64 PNG bytes for png_base64."

Changed6 schema fields changedv2.2.2Aug 22, 2026

changedInput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedInput schema / additionalProperties
```
Added value: +false
```

changedOutput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedOutput schema / anyOf

Added value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "format",
+      "content",
+      "version"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]

addedOutput schema / properties / error

Added value: +{
+  "additionalProperties": {},
+  "description": "Present when the call failed. Absent on success.",
+  "properties": {
+    "code": {
+      "description": "JSON-RPC error code for this failure.",
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    "data": {
+      "additionalProperties": {},
+      "properties": {
+        "reason": {
+          "description": "Machine-readable failure mode. Declared by this tool: `data_too_large`: data exceeds the QR capacity for the chosen errorCorrection level and encoding mode. `raster_too_large`: format is png_base64 and (modules + 2 × margin) × scale exceeds the pixel budget. Other values are possible when a failure originates below the handler.",
+          "examples": [
+            "data_too_large",
+            "raster_too_large"
+          ],
+          "type": "string"
+        },
+        "recovery": {
+          "additionalProperties": {},
+          "description": "Actionable next step for the caller.",
+          "properties": {
+            "hint": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "hint"
+          ],
+          "type": "object"
+        },
+        "retryable": {
+          "description": "Whether retrying may succeed.",
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable description of what went wrong.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "code",
+    "message"
+  ],
+  "type": "object"
+}

removedOutput schema / required

Removed value: -[
-  "format",
-  "content",
-  "version"
-]

Changed1 schema field changedv2.2.0Aug 19, 2026

changedInput schema / properties / scale / description

Previous value: -"Pixels per module for raster (png_base64) output. Ignored for terminal."New value: +"Pixels per module for raster (png_base64) output. Ignored for terminal. png_base64 also bounds the whole image at 2048 px per side, so a dense symbol or a wide margin admits a lower scale than 32."

Changed1 schema field changedv2.0.1Jun 28, 2026

changedInput schema / properties / data / description

Previous value: -"The text or URL to encode. Capped at 2953 bytes — the absolute QR capacity (version 40, level L)."New value: +"The text or URL to encode. 2953 is the absolute ceiling (QR version 40, level L, byte mode); usable capacity drops at higher errorCorrection levels, so over-capacity data is rejected with a typed data_too_large error rather than a generic failure."

Addedv2.0.0Jun 28, 2026

TDQS

A4.7/5.0

Behavior5/5

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

Beyond the readOnlyHint and idempotentHint annotations, the description discloses significant behavioral detail: format-specific output shapes (SVG markup, base64 PNG bytes with mimeType and byteLength, terminal Unicode blocks), typed error conditions (data_too_large, raster_too_large), the pixel-size formula, and the version range reflecting data density. It even clarifies terminal rendering for dark backgrounds. This far exceeds what annotations alone provide.

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 information-dense and front-loaded with the core purpose in the first sentence. Each subsequent sentence introduces a distinct parameter or constraint, and the flow from format to error behavior is logical. It is longer than two sentences, but given the three output formats and several interacting parameters, the length is justified without wasteful 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 tool with 5 parameters, 3 formats, and a moderately complex output, the description is thorough: it covers all parameters, format-specific behaviors, encoding boundaries, and error conditions. An output schema exists, so return values are already documented. No critical information an agent needs to invoke the tool correctly is missing.

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?

Although the schema already has 100% parameter coverage, the description adds meaningful semantics not present in the schema: how scale and margin combine into final image dimensions, which parameters are ignored by which format, how errorCorrection trades capacity against tolerance, and the pixel limit interaction with scale for png_base64. This elevates the description well above the baseline.

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: 'Encode text or a URL into a QR code', which clearly states the tool's function. It goes beyond the title by naming concrete use cases (links, generated identifiers, strings) and enumerating the three output formats. Sibling tools like toolkit_encode_value, toolkit_generate_id, and toolkit_hash_value are clearly different in purpose, so an agent can distinguish this tool without confusion.

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?

The description provides rich context for when to use the tool: what kinds of data are acceptable (links, identifiers, arbitrary strings), what each format yields, and how parameters interact. It does not explicitly state when not to use this tool or name alternative siblings for specific scenarios, but the sibling set is distinct enough that the usage is clear.

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

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