googleapis/mcp-toolbox · error

INTERNAL_ERROR

INTERNAL_ERROR

Error message

error generating manifest: %w

What it means

toolsListHandler wraps any error returned by GenerateListToolsResult with "error generating manifest" and reports it as INTERNAL_ERROR. The underlying cause is one of the manifest-generation failures: missing tool (260), missing source (261), or GetParameters failure (262).

Source

Thrown at internal/server/mcp/v20250326/method.go:124

func pingHandler(id jsonrpc.RequestId) (any, error) {
	return jsonrpc.JSONRPCResponse{
		Jsonrpc: jsonrpc.JSONRPC_VERSION,
		Id:      id,
		Result:  struct{}{},
	}, nil
}

func toolsListHandler(ctx context.Context, id jsonrpc.RequestId, primitiveMgr *primitives.PrimitiveManager, g group.Group, body []byte) (any, error) {
	var req ListToolsRequest
	if err := json.Unmarshal(body, &req); err != nil {
		err = fmt.Errorf("invalid mcp tools list request: %w", err)
		return jsonrpc.NewError(id, jsonrpc.INVALID_REQUEST, err.Error(), nil), err
	}

	urlParams, _ := util.UrlParamsFromContext(ctx)
	listToolsResult, err := GenerateListToolsResult(primitiveMgr, g, urlParams)
	if err != nil {
		err = fmt.Errorf("error generating manifest: %w", err)
		return jsonrpc.NewError(id, jsonrpc.INTERNAL_ERROR, err.Error(), nil), err
	}

	return jsonrpc.JSONRPCResponse{
		Jsonrpc: jsonrpc.JSONRPC_VERSION,
		Id:      id,
		Result:  listToolsResult,
	}, nil
}

// toolsCallHandler generate a response for tools call.
func toolsCallHandler(ctx context.Context, id jsonrpc.RequestId, g group.Group, primitiveMgr *primitives.PrimitiveManager, body []byte, header http.Header) (any, error) {
	if header != nil {
		if clientIP := util.ExtractClientIP(header); clientIP != "" {
			ctx = util.WithClientIP(ctx, clientIP)
		}
	}

View on GitHub (pinned to 8cc6e09de2)

Solutions

1. Inspect the wrapped cause in the error chain to identify the failing tool/source
2. Fix source initialization (connection, credentials) or remove tools referencing dead sources
3. Ensure groups are rebuilt after tool/source registration changes
4. Restart the server after config edits and verify startup logs show all sources/tools registered

// client-side: refresh tools and confirm the server is healthy before listing
const health = await fetch(`${serverUrl}/api/health`)
if (!health.ok) throw new Error("server sources not ready")

try {
  const tools = await client.listTools()
} catch (e) {
  if (e.code === -32603) { // INTERNAL_ERROR: transient source/registry issue
    await waitForServerReady()
    return client.listTools()
  }
  throw e
}

When it happens

Trigger: Any error propagating out of GenerateListToolsResult during tools/list handling — unresolvable tool or source names, or GetParameters failures.

Common situations: Server-side registration inconsistencies after config changes; sources that failed to initialize; custom tools whose schema generation hits a down database.

Related errors

• INTERNAL_ERROR
• INTERNAL_ERROR
• INTERNAL_ERROR
• INTERNAL_ERROR
• METHOD_NOT_FOUND

AI-assisted analysis of googleapis/mcp-toolbox@8cc6e09de2 (2026-09-05). Data as JSON: /api/errors/04cf4acb5ffa321e. Report an issue: GitHub.