MCP Tool Schema Validator
Validate MCP-native tool definitions and JSON Schema 2020-12 structure locally.
MCP 2026-07-28 · JSON Schema 2020-12 · one tool definition
TOOL DEFINITION
Ready to check an MCP-native tool definition.
Checks schema structure, not example instances. References are never fetched or resolved and regex patterns are never executed. Annotations describe claimed behavior; they do not verify safety.
Local text inspection only. Commands, paths, URLs and annotations are untrusted data. Nothing is executed, connected, authenticated or saved.
Enable JavaScript to process locally. No server submission is available.
Review the shape of an MCP-native tool.
Paste one tool definition with a name and inputSchema. The official core Tool type requires an object input root; composition, references, nested objects and arrays remain available inside it. Output schemas may describe any JSON instance type. A no-parameter input can use type object and additionalProperties false.
The current protocol baseline and default schema dialect are shown in the workspace. Meta-schema checks validate keyword structure; they do not execute patterns, resolve references or validate example instances. Unsupported explicit dialects produce errors. Descriptions, icons and annotations are inert data; declared safety properties are never treated as verified behavior.
Boundaries and formats.
Which host profiles are supported?
Cursor uses .cursor/mcp.json. VS Code uses .vscode/mcp.json with a servers root. Portable MCP here means the documented Copilot CLI / Agent Host .mcp.json subset, not a universal configuration standard. Source links and verification dates appear with host selection. Dedicated Claude Desktop validation is deferred.
What stays local?
Inputs, outputs and findings stay in browser memory. Reset and leaving the page clear workspace content. Explicit clipboard and download actions create copies under your control. Ordinary page assets still load from this site.
What are the limits?
Strict JSON only: no comments, trailing commas, duplicate keys or silently rounded numbers. Inputs are capped at 32 KiB UTF-8, 32 nesting levels and 4,000 values. Configurations permit 32 servers, 128 arguments and 64 environment/header entries per server. Conversion output is capped at 128 KiB. No remote MCP inspection is performed.