fix(mcp): register custom tools with a Zod input schema

[valentingoulier]

Problem

@primeng/mcp (which depends on @primeuix/mcp) crashes on startup:

Failed to start PrimeNG MCP Server: Error: Tool get_migration_guide expected a Zod schema or ToolAnnotations, but received an unrecognized object
    at McpServer.tool (.../@modelcontextprotocol/sdk/dist/esm/server/mcp.js)
    at .../@primeuix/mcp/dist/index.js

Reproduced with @modelcontextprotocol/sdk 1.29.0. Because @primeuix/mcp declares "@modelcontextprotocol/sdk": "^1.25.2", fresh/npx installs resolve the latest 1.x and hit the crash.

Root cause

registerCustomTools (packages/mcp/src/index.ts) registers framework-specific tools through the legacy server.tool(name, description, paramsObject, cb) overload, passing a plain object:

const params = { version: { type: 'string', description: '...' }, /* ... */ };
server.tool(tool.name, tool.description, params, handler);

As of @modelcontextprotocol/sdk 1.26, McpServer.tool() validates that third argument: it must be a Zod raw shape or ToolAnnotations. A { type, description } object is neither (its values are objects), so the SDK throws "expected a Zod schema or ToolAnnotations, but received an unrecognized object". PrimeNG's get_migration_guide is the first custom tool registered, so that's where the crash surfaces.

Every other tool in this package already uses server.registerTool(name, { description, inputSchema }, cb) with a Zod shape — only registerCustomTools still used the old path.

Fix

Translate the lightweight { type, description, required?, default? } parameter format into a Zod raw shape and register via registerTool, consistent with the rest of the package:

• maps type → z.string() / z.number() / z.boolean() / z.array(...) / z.record(...)
• a parameter is .optional() unless required: true
• honors default

Verification

• Reproduced the exact crash on main with SDK 1.29.0.
• After the fix, createPrimeMcpServer registers the custom tools without throwing on both SDK 1.29.0 and 1.25.2 (the declared floor).
• tsup build (ESM + dts type-check) passes; Prettier clean against the repo config.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Fixes a startup crash in @primeuix/mcp when used with newer @modelcontextprotocol/sdk versions by registering framework-specific custom tools using a Zod input schema (matching the SDK’s post-1.26 validation rules and the rest of this package’s tool registrations).

Changes:

• Added Zod import and a small mapper (customParameterSchema) to translate custom parameter type strings into Zod schemas.
• Updated registerCustomTools to build a z.ZodRawShape from the lightweight { type, description, required?, default? } parameter format.
• Switched custom tool registration from the legacy server.tool(...) overload to server.registerTool(...) with { description, inputSchema }.

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[breadgrocery]

#228
I’m using primevue-mcp like this 😂:

{
  "command": "npx",
  "args": [
    "-y",
    "-p",
    "@primevue/mcp@4.5.5",
    "-p",
    "@modelcontextprotocol/sdk@1.27.1",
    "primevue-mcp"
  ]
}

It looks like @modelcontextprotocol/sdk >= 1.28.0 introduces API incompatibilities, so pinning @modelcontextprotocol/sdk@1.27.1 works around the issue for now.