MCP tools
mastercss_css_compare
Compare generated CSS for before/after class lists, HTML fragments, or source buffers.
Contract
Compare two class selections using the same active manifest. The result explains generated CSS differences; it does not establish visual equivalence.
Input
Complete input schema
{ "$schema": "http://json-schema.org/draft-07/schema#", "type": "object", "properties": { "context": { "type": "string", "enum": [ "project", "preset" ] }, "beforeClassList": { "type": "string" }, "afterClassList": { "type": "string" }, "beforeHtml": { "type": "string" }, "afterHtml": { "type": "string" }, "beforeContent": { "type": "string" }, "afterContent": { "type": "string" }, "filePath": { "type": "string" } }}Example
Call mastercss_css_compare from a connected MCP client with these arguments:
{ "beforeClassList": "p-sm", "afterClassList": "p-md"}Compare two spacing values under the same manifest.
Output
classes and rules describe additions and removals, invalid lists rejected classes, and css includes before/after text and a diff. The current bytes and bytesDelta fields count UTF-16 code units with JavaScript string lengths, not UTF-8 bytes or compressed transfer sizes.
Every tool returns an object with version: 3, metadata, diagnostics and result. Success payload fields described above live in result.data; failure has result.status: "error" and a required { code, message } error. JSON text equals structuredContent. Tool errors set isError. Metadata records actual context, package/language/binding versions, manifest fingerprint, entries and dependencies; unavailable information is null or an empty array.
Complete output schema
{ "$schema": "http://json-schema.org/draft-07/schema#", "type": "object", "properties": { "version": { "type": "number", "const": 3 }, "metadata": { "type": "object", "properties": { "versions": { "anyOf": [ { "type": "object", "properties": { "languageVersion": { "type": "number" }, "bindingAbiVersion": { "type": "number" }, "packageVersion": { "type": "string" } }, "required": [ "languageVersion", "bindingAbiVersion", "packageVersion" ], "additionalProperties": {} }, { "type": "null" } ] }, "context": { "anyOf": [ { "type": "string", "enum": [ "project", "preset" ] }, { "type": "null" } ] }, "manifestFingerprint": { "type": [ "string", "null" ] }, "entries": { "type": "array", "items": { "type": "string" } }, "dependencies": { "type": "array", "items": { "type": "string" } } }, "required": [ "versions", "context", "manifestFingerprint", "entries", "dependencies" ], "additionalProperties": false }, "diagnostics": { "type": "array", "items": { "type": "object", "properties": { "code": { "type": "string" }, "phase": { "type": "string" }, "severity": { "type": [ "string", "number" ] }, "message": { "type": "string" }, "notes": { "type": "array", "items": { "type": "string" } }, "alternatives": { "type": "array", "items": { "type": "string" } }, "source": { "type": "string" }, "range": { "anyOf": [ { "type": "object", "properties": { "start": { "type": "number" }, "end": { "type": "number" } }, "required": [ "start", "end" ], "additionalProperties": false }, { "type": "object", "properties": { "start": { "type": "object", "properties": { "line": { "type": "number" }, "character": { "type": "number" } }, "required": [ "line", "character" ], "additionalProperties": false }, "end": { "type": "object", "properties": { "line": { "type": "number" }, "character": { "type": "number" } }, "required": [ "line", "character" ], "additionalProperties": false } }, "required": [ "start", "end" ], "additionalProperties": false } ] } }, "required": [ "message" ], "additionalProperties": {} } }, "result": { "oneOf": [ { "type": "object", "properties": { "status": { "type": "string", "const": "success" }, "data": { "type": "object", "properties": { "manifest": { "type": "object", "properties": { "context": { "type": "string", "enum": [ "project", "preset" ] }, "status": { "type": "string", "enum": [ "loaded", "error" ] }, "fingerprint": { "type": [ "string", "null" ] }, "entries": { "type": "array", "items": { "type": "string" } }, "dependencies": { "type": "array", "items": { "type": "string" } }, "versions": { "type": "object", "properties": { "languageVersion": { "type": "number" }, "bindingAbiVersion": { "type": "number" }, "packageVersion": { "type": "string" } }, "required": [ "languageVersion", "bindingAbiVersion", "packageVersion" ], "additionalProperties": {} } }, "required": [ "context", "status", "fingerprint", "entries", "dependencies" ], "additionalProperties": {} }, "classes": { "type": "object", "properties": { "added": { "type": "array", "items": { "type": "string" } }, "removed": { "type": "array", "items": { "type": "string" } }, "unchanged": { "type": "array", "items": { "type": "string" } } }, "required": [ "added", "removed", "unchanged" ], "additionalProperties": false }, "css": { "type": "object", "properties": { "changed": { "type": "boolean" }, "before": { "type": "object", "properties": { "bytes": { "type": "number" }, "text": { "type": "string" } }, "required": [ "bytes" ], "additionalProperties": {} }, "after": { "type": "object", "properties": { "bytes": { "type": "number" }, "text": { "type": "string" } }, "required": [ "bytes" ], "additionalProperties": {} }, "bytesDelta": { "type": "number" }, "diff": { "type": "string" } }, "required": [ "changed", "before", "after", "bytesDelta", "diff" ], "additionalProperties": false }, "rules": { "type": "object", "properties": { "added": { "type": "array", "items": { "type": "string" } }, "removed": { "type": "array", "items": { "type": "string" } }, "unchanged": { "type": "number" } }, "required": [ "added", "removed", "unchanged" ], "additionalProperties": false }, "summary": { "type": "object", "propertyNames": { "type": "string" }, "additionalProperties": { "$ref": "#/definitions/__schema0" } } }, "required": [ "manifest", "classes", "css", "rules", "summary" ], "additionalProperties": {} } }, "required": [ "status", "data" ], "additionalProperties": false }, { "type": "object", "properties": { "status": { "type": "string", "const": "error" }, "error": { "type": "object", "properties": { "code": { "type": "string" }, "message": { "type": "string" } }, "required": [ "code", "message" ], "additionalProperties": false } }, "required": [ "status", "error" ], "additionalProperties": false } ] } }, "required": [ "version", "metadata", "diagnostics", "result" ], "additionalProperties": false, "definitions": { "__schema0": { "anyOf": [ { "type": "string" }, { "type": "number" }, { "type": "boolean" }, { "type": "null" }, { "type": "array", "items": { "$ref": "#/definitions/__schema0" } }, { "type": "object", "propertyNames": { "type": "string" }, "additionalProperties": { "$ref": "#/definitions/__schema0" } } ] } }}Project context and lifecycle
This operation does not write workspace files.
The local stdio server uses the workspace passed to --root. Confirm the root and intended CSS entries with mastercss_workspace_info before relying on project-dependent values.
See the MCP workflow guide for client setup and the preview/apply workflow.